Compressors DKRCC.pf.000.G3.02 520H6345

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DKRCC.PF.000.G3.02 / 520H6345

Fitters Notes Compressors

1

Compressors

Contents Page

Household compressors general inormation 3

Household compressors how to handle 21

Household compressors special requirements or R290 systems 39

Commercial compressors general inormation 49

This chapter is divided into our sections:


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Fitters Notes Danoss compressors

Notes


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Compressors

Contents Page

1 0 G e n e r a l 4

20 Compressor 4

2 1 D e n o m i n a t i o n 5

22 Low and High starting torque 623 Motor protector and winding temperature 6

24 Rubber grommets 6

25 Minimum ambient temperature 6

30 Compressor check-up 7

31 Winding protector cut-out 7

32 PTC and protector interaction 7

33 Check o winding protector and resistance 7

40 Opening the rerigerating system 7

41 Flammable rerigerants 8

50 Mounting 851 Connectors 8

52 Driting out connectors 10

53 Tube adaptors 10

54 Brazing alloy 10

55 Soldering 11

56 LOKRING connections 12

57 Driers 12

58 Driers and rerigerants 13

59 Capillary tube in drier 13

60 Electrical equipment 14

61 LST starting device 14

62 HST starting equipment 15

63 HST CSR starting equipment 17

64 Equipment or SC twin compressors 17

65 Electronic unit or variable speed compressors 18

70 Evacuation 18

71 Vacuum pumps 19

80 Charging o rerigerant 19

81 Maximum rerigerant charge 19

82 Closing the process tube 19

90 Testing 2091 Testing o the appliance 20


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When a compressor has to be installed in newappliances normally sucient time is availableto choose the right compressor type romdatasheets and make sucient testingContrary when a aulty compressor has to be

replaced it can in many cases be impossible toget the same compressor type as the originalIn such cases it is necessary to compare relevantcompressor catalogue data

Long lietime or a compressor can be expectedi the service work is done in the right way andcleanness and dryness o the components aretaken into consideration

The service technician has to observe theollowing when choosing a compressorType o rerigerant, voltage and requency,application range, compressor displacement/capacity, starting conditions and cooling

conditionsI possible use the same rerigerant type as in theaulty system

The programme o Danoss compressors consistso the basic types P, T, N, F, SC, SC Twin and GS

Danoss 220 V compressors have a yellow label

with inormation o the type designation, voltageand requency, application, starting conditions,rerigerant and code number

The 115 V compressors have a green label

LST/HST mentioned both means that the startingcharacteristics are depending on the electricalequipment

I the type label has been destroyed, thecompressor type and the code number canbe ound in the stamping on the side o thecompressor

See picture Am0_0025b

Composition o line 1:

H4485: Compressor type inormation(eg 102H4485 = H4485)

C: internal code

Composition o line 2:Production date(week, year, day, hour eg 051D11)

2.0Compressor

1.0General

Am0_0024

Am0_0025

Am0_0025b


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Compressors

2.1Denomination

Compressor platormBD, P, T, F, N, S, GS

Protection locationL, R, C = Int Winding protectorF = Ext Winding protectorLV = Variable speed

Optimization levelE = Energy optimizationS = Semi-direct intakeX, Y, U = High energy optimized

Nominal displacement in cm3

(15/15 = TWIN compressors)

N L E 9 FF R 7,5 G KS C 15 CN X . 2

GenerationBlank, 2, 3, 4

K = Low Starting Torque (capillary tubes)X = High Starting Torque

Application RangeC = LBP R22CL = LBP R404/R507CM = LBP R22CN = LBP R290D = HBP R22DL = HBP R404A/R507, R407CF = HBP/(MBP) R134aFT = LBP tropical R134aG = LBP/MBP/HBP R134aGH = Heat pumps R134aGHH = Heat pumps optimized R134aK = LBP/(MBP) R600aKT = LBP/(MBP), tropical R600aMF = MBP R134aMK = MBP R600aML = MBP R404A/R507MN = MBP R290S = LBP/HBP (service) R426A, R401A/R401B, R409A/R409BST = LBP tropical (service) R426A, R401A/R401B, R409A/R409B

The rst letter o the denomination (P, T, N, F, Sor G) indicates compressor series whereas thesecond letter indicates motor protection placing

E, U, Y and X mean dierent energy optimizationsteps S means semi direct suction V meansvariable speed compressors On all thesementioned types the indicated suction connectorhas to be used Using the wrong connector assuction connector will lead to reduced capacity

and eciencyA number indicates the displacement in cm3,but or PL compressors the number indicates thenominal capacity

The letter ater the displacement indicates whichrerigerant must be used as well as the eld oapplication or the compressor (See example)LBP (Low Back Pressure) indicates the range olow evaporating temperatures, typically -10Cdown to -35C or even -45C, or use in reezersand rerigerators with reezer compartments

MBP (Medium Back Pressure) indicates the rangeo medium evaporating temperatures, typically

-20C up to 0C, such as in cold cabinets, milkcoolers, ice machines and water coolers

HBP (High Back Pressure) indicates highevaporating temperatures, typically -5C up to+15C, such as in dehumidiers and some liquidcoolers

T as extra character indicates a compressorintended or tropical application This means highambient temperatures and capability o working

with more unstable power supplyThe nal letter in the compressor denominationprovides inormation on the starting torque I,as principal rule, the compressor is intended orLST (Low Starting Torque) and HST (High StartingTorque), the place is let empty The startingcharacteristics are depending on the electricalequipment chosen

K indicates LST (capillary tube and pressureequalization during standstill) and Xindicates HST (expansion valve or no pressureequalization)


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2.2Low and High startingtorque

Description o the dierent electrical equipmentsshown can be ound in the datasheets or thecompressors See also section 60

Low starting torque (LST) compressors mustonly be used in rerigerating systems having

capillary tube throttling device where pressureequalization is obtained between suction anddischarge sides during each standstill period

A PTC starting device (LST) requires that thestandstill time is at least 5 minutes, since this isthe time necessary or cooling the PTC

The HST starting device, which gives thecompressor a high starting torque, must always

be used in rerigeration systems with expansionvalve, and or capillary tube systems without ullpressure equalization beore each start

High stating torque (HST) compressors arenormally using a relay and starting capacitor as

starting deviceThe starting capacitors are designed or shorttime cut-in

17% ED, which is stamped onto the startingcapacitor, means or instance max 10 cut-ins perhour each with a duration o 6 seconds

2.3Motor protector andwinding temperature

Most o the Danoss compressors are equippedwith a built-in motor protector (windingprotector) in the motor windings See alsosection 21

At peak load the winding temperature mustnot exceed 135C and at stable conditions thewinding temperature must not exceed 125CSpecic inormation on some special types can

be ound in the collection o data sheets

2.4Rubber grommets

3327-2

9

Compressor bas rommet sleeve

Washer Nut M6

Cabinet base Screw M6 x 25 Rubber grommet

Stand the compressor on the base plate until itis tted

This reduces the risk o oil coatings inside theconnectors and associated brazing problems

Place the compressor on its side with theconnectors pointing upwards and then t therubber grommets and grommet sleeves on thebase plate o the compressor

Do not turn the compressor upside down

Mount the compressor on the baseplate o theappliance

Am0_0026

Am0_0027

2.5Minimum ambient

temperature

Allow the compressor to reach a temperatureabove 10C beore starting the rst time to avoid

starting problems


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Compressors

3.0Compressor check-up

I the compressor does not operate, it could havemany reasons Beore replacing the compressor, itshould be made sure, that it is deect

For easy ailure location, please see the sectionTrouble shooting

3.1Winding protector cut-out I the winding protector cuts out while thecompressor is cold, it can take approx 5 minutesor the protector to reset

I the winding protector cuts out while thecompressor is warm (compressor housing above80C) the resetting time is increased Up toapprox 45 minutes may pass beore reset

3.2PTC and protectorinteraction

The PTC starting unit requires a cooling time o 5minutes beore it can restart the compressor withull starting torque

Short time power supply cut os, not longenough to allow the PTC to cool down, can resultin start ailure or up to 1 hour

The PTC will not be able to provide ull actionduring the rst protector resets, as they typicallydo not allow pressure equalization also Thus theprotector trips until the reset time is longenough

This mismatch condition can be solved byunplugging the appliance or 5 to 10 minutestypically

3.3Check o winding protectorand resistance

In the event o compressor ailure a check ismade by means o resistance measurementdirectly on the current lead-in to see whetherthe deect is due to motor damage or simply atemporarily cut out o the winding protector

I tests with resistance measurement reveal aconnection through the motor windings rompoint M to S o the current lead-in, but brokencircuit between point M and C and S and C thisindicates that the winding protector is cut outThereore, wait or resetting

M S

C

Start winding

Winding protector

Main winding

Am0_0028

4.0Opening the rerigeratingsystem

Never open a rerigerating system beore allcomponents or the repair are available

Compressor, drier and other system componentsmust be sealed o until a continuous assemblycan occur

Opening a deect system must be done indierent ways depending on the rerigerant used

Fit a service valve to the system and collect thererigerant in the right way

I the rerigerant is fammable it can be releasedoutside in the open air through a hose i theamount is very limited

Then fush the system with dry nitrogen


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4.1Flammable rerigerants

R600a and R290 are hydrocarbons Thesererigerants are fammable and are only allowedor use in appliances which ull the requirementslaid down in the latest revision o EN/IEC 60335-2-24 (To cover potential risk originated rom the

use o fammable rerigerants)

Consequently, R600a and R290 are only allowedto be used in appliances designed or thisrerigerant and ull the above-mentionedstandard R600a and R290 are heavier than airand the concentration will always be highest at

the foor The fammability limits are approx asollows:

Rerigerant R600a R290

Lower limit 15% by vol (38 g/m3) 21% by vol (39 g/m3)

Upper limit 85% by vol (203 g/m3) 95% by vol (177 g/m3)

Ignition temperature 460C 470C

In order to carry out service and repair on R600aand R290 systems the service personnel must beproperly trained to be able to handle fammablererigerants

This includes knowledge on tools, transportationo compressor and rerigerant, and the relevant

regulations and saety precautions when carryingout service and repair

Do not use open re when working withrerigerants R600a and R290!

Danoss compressors or the fammablererigerants R600a and R290 are equipped with ayellow warning label as shown

The smaller R290 compressors, types T and N, areLST types These oten need a timer to ensuresucient pressure equalization time

For urther inormation, please see the section

Practical Application o Rerigerant R290Propane in Small Hermetic Systems

R600a

R290

5.0Mounting

Soldering problems caused by oil in theconnectors can be avoided by placing thecompressor on its base plate some time beoresoldering it into the system

The compressor must never be placed upsidedown The system should be closed within 15minutes to avoid moisture and dirt penetration

5.1Connectors

The positions o connectors are ound in thesketches C means suction and must always beconnected to the suction line

E means discharge and must be connected tothe discharge line D means process and is usedor processing the system

TL

E

Cor

D

Dor

C

PL

C

E

D

NL

C

ED

FR

E

CD

SC

D C

E

C D

E

TLSCD

E

GS

Am0_0029

Am0_0030

Am0_0031


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Compressors

Most Danoss compressors are equipped withtube connectors o thick-walled, copper-platedsteel tube which have a solderability whichcomes up to that o conventional copperconnectors

The connectors are welded into the compressorhousing and weldings cannot be damaged byoverheating during soldering

The connectors have an aluminium cap sealing(capsolut) which gives a tight sealing The sealingsecures that the compressors have not beenopened ater leaving Danoss production lines Inaddition to that, the sealing makes a protectingcharge o nitrogen superfuous

The capsoluts are easily removed with anordinary pair o pliers or a special tool as shownThe capsolut cannot be remounted When the

seals on the compressor connectors are removedthe compressor must be mounted in the systemwithin 15 minutes to avoid moisture and dirtpenetration

Capsolut seals on connectors must never be letin the assembled system

5.1Connectors(continued)

Am0_0032

Oil coolers, i mounted (compressors rom 7 cm3displacement), are made o copper tube and thetube connectors are sealed with rubber plugs Anoil-cooling coil must be connected in the middleo the condenser circuit

SC Twin compressors must have a check valvein the discharge line to compressor no 2 I achange in the starting sequence betweencompressor no 1 and no 2 is wanted a checkvalve has to be placed in both discharge lines

Am0_0033

In order to have optimum conditions orsoldering and to minimize the consumptiono soldering material, all tube connectors onDanoss compressors have shoulders, as shown

Am0_0034


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5.2Driting out connectors

It is possible to drit out the connectors havinginside diameters rom 62 mm to 65 mm whichsuit 14 (635 mm) tube, but we advise againstdriting out the connectors by more than 03 mm

During driting it is necessary to have a suitablecounterorce on the connectors so that they dontbreak o

A dierent solution to this problem would be toreduce the diameter o the end o the connectortube with special pliers

Am0_0035

5.3Tube adaptors

Instead o driting out the connectors or reducingthe diameter o the connection tube, copperadapter tubes can be used or service

A 6/65 mm adaptor tube can be used where acompressor with millimetre connectors (62 mm)is to be connected to a rerigerating system with14 (635 mm) tubes

A 5/65 mm adaptor tube can be used where acompressor with a 5 mm discharge connector isto be connected to a 14 (635 mm) tube

Am0_0036

Am0_0037

5.4

Brazing alloy

For soldering the connectors and copper tubes

solders having a silver content as low as 2% cantheoretically be used but with 15% is preerredThis means that the so-called phosphor solderscan also be used when the connecting tube ismade o copper

I the connecting tube is made o steel, a solderwith high silver content which does not containphosphor and which has a liquidus temperaturebelow 740C is required For this also a fux isneeded


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Compressors

5.5Soldering

The ollowing are guidelines or soldering osteel connectors dierent rom soldering copperconnectors

During heating, the temperature should be kept

as close to the melting point o the solder aspossible

Am0_0038

Use the sot heat in the torch fame whenheating the joint

Distribute the fame so at least 90% o the heatconcentrates around the connector and approx10% around the connecting tube

Am0_0039

When the connector is cherry-red (approx 600C)apply the fame to the connecting tube or a ewseconds

Am0_0040

Continue heating the joint with the sot fameand apply solder

Am0_0041

Overheating will lead to surace damage, sodecreasing the chances o good soldering

Draw the solder down into the solder gap byslowly moving the fame towards the compressorthen completely remove the fame


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5.6LOKRING connections

System containing the fammable rerigerantsR600a or R290 must not be soldered In suchcases a LOKRING connection as shown can beusedNewly made systems can be soldered as usual,

as long as they have not been charged withfammable rerigerant

Charged systems are never to be opened by useo the fame Compressors rom systems withfammable rerigerant have to be evacuated toremove the rerigerant residues rom the oil

Assembly jaws

Bolt

Tool

Tube LOKRING LOKRING Joint

Tube LOKRING LOKRING TubeJoint

Beore theassembly

Ater theassembly

LOKRING union joint

5.7Driers

Danoss compressors are expected to be used inwell-dimensioned rerigerant systems including adrier containing an adequate amount and type odesiccant and with a suitable quality

The rerigerating systems are expected to have adryness corresponding to 10 ppm As a max limit20 ppm is accepted

The drier must be placed in a way ensuring thatthe direction o fow o the rerigerant ollowsgravitation

Thus the MS beads are prevented rom movingamong themselves and in this way making dustand possible blockage at the inlet o the capillarytube At capillary tube systems this also ensures aminimal pressure equalizing time

Especially pencil driers should be chosen careully

to ensure proper quality In transportable systemsonly driers approved or mobile application areto be used

A new drier must always be installed when arerigeration system has been opened

Am0_0043

Am0_0042


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Compressors

5.8Driers and rerigerants

Water has a molecular size o 28 ngstrmAccordingly, Molecular Sieves with a pore sizeo 3 ngstrm will be suitable or normally usedrerigerants

MS with a pore size o 3 ngstrm can besupplied by the ollowing,

UOP Molecular Sieve Division (ormer Union Carbide)

25 East Algonquin Road, Des Plaines

Illinois 60017-5017, USA 4A-XH7 4A-XH9

R22, R502

R134a

HFC/HCFC blends

R290, R600a

Grace Davison Chemical

W.R.Grace & Co, P.O.Box 2117, Baltimore

Maryland 212203 USA 574 594

R22, R502

R134a HFC/HCFC blends

R290, R600a

CECA S.A

La Deense 2, Cedex 54, 92062 Paris-La Deense

France NL30R Siliporite H3R

R22, R502

R134a

HFC/HCFC blends

R290, R600a

Driers with the ollowing amount o desiccantsare recommended

Compressor Drier

PL and TL 6 gram or more

FR and NL 10 gram or more

SC 15 gram or more

In commercial systems larger solid core driers areoten used These are to be used or the

rerigerants according to the manuacturersinstructions I a burn-out lter is needed in arepair case, please contact the supplier or detailinormation

5.9Capillary tube in drier

Special care should be taken when soldering thecapillary tube When mounting the capillary tubeit should not be pushed too ar into the drier,thus touching the gaze or lter disc, causing ablockage or restriction I, on the other hand,the tube is only partly inserted into the drier,blockage could occur during the soldering

This problem can be avoided by making a stopon the capillary tube with a pair o special pliersas shown

Am0_0044


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6.0Electrical equipment

For inormation on the right starting devices,please see Datasheets or the compressorNever use a starting device o and oldcompressor, because this may cause acompressor ailure

No attempt must be made to start thecompressor without the complete starting

equipment For saety reasons the compressormust always be earthed or otherwise additionallyprotected Keep away infammable material romthe electrical equipment

The compressor must not be started undervacuum

6.1LST starting device

Compressors with internal motor protector.The below drawings show three types o deviceswith PTC starters

Mount the starting device on the current lead-ino the compressor

Pressure must be applied to the centre o thestarting device so that the clips are not deormed

Mount the cord relie on the bracket under thestarting device

On some energy optimized compressors a runcapacitor is connected across the terminals N andS or lower power consumption

Pressure must be applied to the centre o thestarting device when dismantling so that theclips are not deormed

Place the cover over the starting device andscrew it to the bracket

N

N LC

b

d

a1

a1

Winding protector

Start windingMain winding

g

10 11

1312

14

b

d

a2

c

c

Main winding Start windingWinding protector

N

N LC

b

d

a1

a1

Winding protector

Start windingMain winding

Am0_0045 Am0_0046

Am0_0047 Am0_0048


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Compressors

6.3HST CSR starting equipment

Mount the terminal box on the current lead-inNote that the leads must ace upwardsMount the cord relie in the bracket underterminal box Place the cover (See g F)

6.4Equipment or SC twincompressors

The use o a time delay (eg Danoss 118U0082) isrecommended or starting the second section (15seconds time delay)

I time delay is used, the connection on theterminal board between L and 1 must beremoved rom the compressor no 2 connectionbox

I thermostat or capacity control is used, theconnection on the terminal board between 1 and2 must be removed

Am0_0058

M

12

10 11

13

14

12

14

10 11

13

1

2

N

L

1

2

N

L

1 1

2 2

N N

L L

2 1 3

BA

1 2

C

D

E

F

5 2

14

5 2

14

1 1

2 2

N N

L L

1 1

2 2

N N

L L

M

B

2 1 3C

D

E

A

F

1

A: Saety pressure controlB: Time delay relayC: BlueD: Black

E: BrownF: Remove wire L-1 i time delay isusedRemove wire 1-2 i thermostat 2is used

Am0_0059

Am0_0060


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6.5Electronic unit orvariable speed compressors

The electronic unit provides the NLV compressorswith a high starting torque (HST) which meansthat a pressure-equalization o the system beoreeach start is not necessary

The variable speed compressor motor iselectronically controlled The electronic unit hasbuilt-in overload protection as well as thermalprotection In case o activation o the protectionthe electronic unit will protect the compressormotor as well as itsel When the protection has

been activated, the electronic unit automaticallywill restart the compressor ater a certain time

The compressors are equipped with permanentmagnet rotors (PM motor) and 3 identical stator

windings The electronic unit is mounted directlyon the compressor and controls the PM motor

Connecting the motor directly to AC mains, byault, will damage the magnets and lead to dras-tically reduced eciency, or even no unctioning

Am0_0061

7.0Evacuation

Ater brazing, evacuation o the rerigerationsystem is startedWhen a vacuum below 1 mbar is obtained thesystem is pressure equalized beore the nalevacuation and charging o rerigerantI a pressure test has been perormed directlybeore evacuation, the evacuation process is to

be started smoothly, with low pumping volume,to avoid oil loss rom the compressorMany opinions exist how evacuation can becarried out in the best wayDependent on the volume conditions o thesuction and the discharge side in the rerigerationsystem, it might be necessary to choose one othe ollowing procedures or evacuationOne-sided evacuation with continuousevacuation until a suciently low pressure in thecondenser has been obtained One or more shortevacuation cycles with pressure equalization inbetween is necessaryTwo-sided evacuation with continuousevacuation until a suciently low pressure has

been obtained

These procedures naturally require a gooduniorm quality (dryness) o the componentsusedThe below drawing shows a typical course oa one-sided evacuation rom the process tubeo the compressor It also shows a pressuredierence measured in the condenser This

can be remedied by increasing the numbers opressure equalizationsThe dotted line shows a procedure where twosides are evacuated simultaneouslyWhen the time is limited, the nal vacuum to beobtained is only dependent on the capacityo the vacuum pump and the content o noncondensable elements or rerigerant residues inthe oil chargeThe advantage o a two-sided evacuation isthat it is possible to obtain a considerably lowerpressure in the system within a reasonableprocess timeThis implies that it will be possible to build a leakcheck into the process in order to sort out leaks

beore charging the rerigerant

Am0_0062


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Compressors

The below drawing is an example o a pre-evacuation process with built-in leak test

The level o vacuum obtained depends onthe process chosen Two-sided evacuation isrecommended

7.0Evacuation(continued)

Am0_0062

7.1Vacuum pumps

An explosion-sae vacuum pump must be usedor systems with the fammable rerigerantsR600a and R290

The same vacuum pump can be used or allrerigerants i it is charged with Ester oil

8.0Charging o rerigerant

Always charge the system with type andamount o rerigerant recommended by themanuacturer In most cases the rerigerantcharge is indicated on the type label o theappliance

Charging can be done according to volume orby weight Use a charging glass or charging byvolume Flammable rerigerants must be chargedby weight

8.1

Maximum rerigerant charge

I the max rerigerant charge is exceeded the oil

in the compressor may oam ater a cold start andthe valve system could be demaged

The rerigerant charge must never be too large

to be contained on the condenser side o thererigeration system Only the rerigerant amountnecessary or the system to unction must becharged

Compressor Maximum rerigerant charge

R134a R600a R290 R404A

P 300 g 150 g

T 400 g* 150 g 150 g 400 g

N 400 g* 150 g 150 g 400 g

F 900 g 150 g 850 g

SC 1300 g 150 g 1300 g

GS 2000 g 2000 g

SC-Twin 2200 g 2200 g

*) Single types with higher limits available, see data sheets.

8.2Closing the process tube

For the rerigerants R600a and R290 the closingo the process tube can be done by means o aLOKRING connection

Soldering is not allowed on systems withfammable rerigerants


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9.0Testing

Hermetic rerigerating systems must be tight I adomestic appliance shall unction over areasonable lietime, it is necessary to haveleak rates below 1 gram per year So leak testequipment o a high quality is required

All connections must be tested or leaks with aleak testing equipment This can be done with anelectronic leak testing equipment

The discharge side o the system (rom dischargeconnector to the condenser and to the drier)must be tested with the compressor runningThe evaporator, the suction line and thecompressor must be tested during standstill andequalized pressure

I rerigerant R600a is used, leak test should bedone with other means than the rerigerant, eghelium, as the equalizing pressure is low, so otenbelow ambient air pressure Thus leaks would notbe detectable

9.1Testing o the appliance

Beore leaving a system it must be checked thatcooling down o the evaporator is possible andthat the compressor operates satisactory on thethermostat

For systems with capillary tube as throttlingdevice it is important to check that the system isable to pressure equalize during standstill periodsand that the low starting torque compressor isable to start the system without causing trips onthe motor protector


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Compressors

Contents Page

10 General 23

11 Fault location 23

12 Replacement o thermostat 24

13 Replacement o electrical equipment 2514 Replacement o compressor 25

15 Replacement o rerigerant 25

20 Rules or repair work 27

21 Opening o the system 27

22 Brazing under an inert protective gas 28

23 Filter drier 28

24 Moisture penetration during repair 29

25 Preparation o compressor and electrical equipment 29

26 Soldering 30

27 Evacuation 3128 Vacuum pump and vacuum gauge 31

30 Handling o rerigerants 32

31 Charging with rerigerant 32

32 Maximum rerigerant charge 32

33 Test 33

34 Leak test 33

40 Replacement o deective compressor 34

41 Preparation o components 34

42 Removal o charge 34

43 Removal o deective compressor 34

44 Removal o rerigerant residues 34

45 Removal o lter drier 34

46 Cleaning o solder joints and reassembly 34

50 Systems contaminated with moisture 35

51 Low degree o contamination 35

52 High degree o contamination 35

53 Drying o compressor 36

54 Oil charge 36

60 Lost rerigerant charge 37

70 Burnt compressor motor 38

71 Oil acidity 3872 Burnt system 38


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Notes


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Compressors

Repairs o rerigerators and reezers demandskilled technicians who are to perorm thisservice on a variety o dierent rerigerator typesPreviously service and repair were not as heavilyregulated as now due to the new rerigerants,

some o which are fammable

Fig 1 shows a hermetic rerigeration system withcapillary tube as expansion device This systemtype is used in most household rerigeratorsand in small commercial rerigerators, ice creamreezers and bottle coolersFig 2 shows a rerigeration system using athermostatic expansion valve This system type ismainly used in commercial rerigeration systems

Repair and service is more dicult than newassembly, since working conditions in the eldare normally worse than in a production site or ina workshop

A precondition or satisactory service work isthat the technicians have the right qualications,ie good workmanship, thorough knowledge othe product, precision and intuitionThe purpose o this guide is to increase theknowledge o repair work by going through thebasic rules The subject matter is primarily dealtwith reerence to repair o rerigeration systemsor household rerigerators in the eld but manyo the procedures may also be transerred tocommercial hermetic rerigeration installations

1.0General

1.1Fault location

Fig. 3: Pressure gauges, service valve, multimeter and leak tester

Beore perorming any operations on arerigeration system the progress o the repair

should be planned, ie all necessary replacementcomponents and all resources must be availableTo be able to make this planning the ault in thesystem must rst be known For ault locationtools must be available as shown in g 3 Suctionand discharge manometer, service valves,multimeter (voltage, current and resistance) anda leak tester

In many cases it can be concluded rom the usersstatements which aults could be possible, and

or most aults a relatively accurate diagnosis canbe made However, a precondition is that theservice technician has the necessary knowledgeo the unctioning o the product and that theright resources are available An elaborate aultlocation procedure will not be gone throughhere, however, the most common aults wherethe compressor does not start or run arementioned in the ollowing

Main switch releasedOne potential ault may be a deective use, andthe reason may be a ault in the motor windingsor in the motor protector, a short circuit or aburnt current lead-in on the compressor Theseaults require the compressor to be replaced

CompressorStarting device and compressor motor may bea wrong choice Compressor motor or windingprotector may be deective, and the compressormay be mechanically blocked

Frequent reasons or reduced rerigerationcapacity are coking or copper platings dueto moisture or non-condensable gases in thesystem

Blown gaskets or broken valve plates are due totoo high peak pressures and short-time pressure

peaks as a result o liquid hammering in thecompressor, which may be due to a too highrerigerant charge in the system or a blockedcapillary tube

Fig. 1: Hermetic rerigeration system with capillary tubes

Fig. 2: Hermetic rerigeration system with expansion valve

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1.2Replacement othermostat

The voltage may be too low or the pressure toohigh or the compressor Non equalized pressurecauses the motor protector to cut out ater eachstart and will eventually result in a burnt motorwinding A deective an will also aect the

compressor load and may cause motor protectorcut outs or blown gaskets

In case o unsuccessul start and cold compressorup to 15 minutes may pass until the windingprotector cuts the compressor out I the windingprotector cuts out when the compressor is hot upto 45 minutes may pass until the protector cutsthe compressor in againBeore starting a systematic ault location it is agood rule to cut o the voltage to the compressoror 5 minutes This ensures the PTC starting device,i any, to be cooled suciently to be able to startthe compressor

Should a brie power ailure occur within therst minutes o a rerigeration process, a confictsituation (interlocking) may arise between theprotector and the PTC A compressor with a PTCstarting device cannot start in a system that isnot pressure-equalized, and the PTC cannot coolso quickly In some cases it will take up to 1 houruntil the rerigerator runs normally again

High and low pressure switchesCut out o the high pressure switch may be due totoo high condensing pressure, probably caused bylack o an cooling A cut-out low pressure switchmay be due to insucient rerigerant charge,leakage, evaporator rost ormation or partial

blockage o the expansion device

Beore replacing the compressor it is a good ideato check the thermostat

A simple test can be made by short-circuitingthe thermostat so the compressor gets powerdirectly I the compressor can operate like this thethermostat must be replaced

For replacement it is essential to nd a suitabletype, which may be dicult with so manythermostat types in the market To make thischoice as easy as possible several manuacturers,

ie Danoss, have designed so-called servicethermostats supplied in packages with allaccessories necessary or thermostat service

1.1Fault location(continued)

The cut out may also be due to a mechanicalailure, wrong dierence setting, wrong cut-outpressure setting or irregularities in pressure

Thermostat

A deective or incorrectly set thermostat mayhave cut out the compressor I the thermostatloses sensor charge or i the temperature settingis too high, the compressor will not start Theault may also be caused by a wrong electricalconnectionToo low a dierential (dierence between cutin and cut out temperature) will cause too shortcompressor standstill periods, and in connectionwith a LST compressor (low starting torque) thismight lead to starting problemsSee also point 12 Replacement o thermostat

For urther details please reer to Fault locationand prevention in rerigeration circuits with

hermetic compressorsA careul ault determination is necessary beoreopening the system, and especially beoreremoving the compressor rom the system Repairsrequiring operations in a rerigeration system arerather costly Beore opening old rerigerationsystems it may thereore be appropriate to makesure that the compressor is not close to breakingdown though it is still unctionalAn estimation can be made by checking thecompressor oil charge A little oil is drained in toa clean test glass and is compared with a newoil sample I the drained oil is dark, opaque andcontaining impurities, the compressor should be

replaced

With eight packages, each covering one type orerigerator and application, service can be madeon almost all common rerigerators See g 4The application area o each thermostat coversa wide range o thermostat types Moreover,the thermostats have a temperature dierentialbetween cut in and cut out sucient to ensuresatisactory pressure equalization in the systemstandstill periods

In order to achieve the requested unctionthe thermostat sensor (the last 100 mm o the

capillary tube) must always be in close contactwith the evaporator

When replacing a thermostat it is importantto check whether the compressor operatessatisactorily both in warm and cold position, andwhether the standstill period is sucient or thesystem pressure equalization when using a LSTcompressor

With most thermostats it is possible to obtaina higher temperature dierential by adjustingthe dierential screw Beore doing this it isrecommended to seek advice in the thermostatdata sheet which way the screw must be turned

Another way o obtaining a higher dierentialis to place a piece o plastic between the sensorand the evaporator, since 1 mm plastic results inapprox 1C higher dierential

Fig. 4: Service thermostats

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Compressors

1.3Replacement o electricalequipment

1.4Replacement o compressor

The cause or aults may also be ound in theelectrical equipment o the compressor, where itis possible to replace starting relay/PTC startingdevice, motor protector, starting or run capacitorA damaged starting capacitor may be caused

by too low thermostat dierential setting, sincethe starting capacitor must maximum cut in 10times/hour

I a ault is ound on the winding protector builtinto many hermetic compressors the entirecompressor must be replaced

When replacing a compressor the electrical

equipment must be replaced as well, sinceold electrical equipment used with a newcompressor may cause a compressor breakdownlater

I the ailure is a deective compressor, thetechnician must take care to select a compressorwith the correct characteristics or the applianceI a compressor corresponding to the deectiveone is available, and i it is intended or a nonregulated rerigerant, no urther problems willarise However, in many cases it is impossibleto provide the same compressor type as thedeective one, and in this case the service

technician must be aware o some actorsI it is a question o changing rom onecompressor manuactured to another it canbe dicult to select the correct compressor,and thereore dierent parameters have to beconsideredCompressor voltage and requency mustcorrespond to voltage and requency on locationThen the application area must be considered(low, medium or high evaporating temperatures)The cooling capacity must correspond to the oneo the previous compressor, but i the capacity

is unknown a comparison o the compressordisplacements will be applicable It would beappropriate to select a compressor slightly largerthan the deective oneFor a capillary tube system with pressureequalization during the standstill periods a LSTcompressor (low starting torque) can be used,and or a system with expansion valve or nopressure equalization a HST compressor (high

starting torque) is to be chosenO course a HST compressor may also be used ina capillary tube systemFinally the compressor cooling conditions mustalso be considered I the system has an oilcooling arrangement, a compressor with an oilcooler must be selectedIn a service situation a compressor with anoil cooler instead o a compressor without oilcooler can be used without problems, since thespiral can be completely ignored when it is notrequired

1.5

Replacement orerigerant

The best solution or a repair is to select the same

rerigerant as used in the present systemDanoss compressors are supplied or weresupplied in versions or the rerigerants R12, R22,R502, R134a, R404A/R507/R407C and or thefammable rerigerants R290 and R600aThe rerigerants R12 and R502, which are coveredby the regulations in the Montreal Protocol,may be used in very ew countries only, and thererigerants will eventually be phased out oproduction altogetherFor heat pump systems the rerigerant R407C isnow used instead o R22 and R502The more environmentally acceptable rerigerantR134a has replaced R12, and the rerigerantsR404A and R507 have replaced R22 and R502 in

many applications

The ammable rerigerants R290 and R600aMaximum charge o these rerigerants in asystem is 150 g according to todays relevantappliance standards, and they must be applied insmall rerigerators only

Blend rerigerants

Rerigerant Trade name Composition Replacing Application area Applicable oils

R401A Suva MP39 R22, R152a, R124 R12 L - M Alkylbenzene

R401B Suva MP66 R22, R152a, R124 R12 L Alkylbenzene

R402A Suva HP80 R22, R125, R290 R502 LPolyolester

Alkylbenzene

R402B Suva HP81 R22, R125, R290 R502 L - MPolyolester

Alkylbenzene

The famable rerigerants must only be used in

rerigeration systems meeting the requirementso EN/IEC 60335-2-24 or -2-89, including demandsor fammable rerigerants and the servicepersonnel must be specially trained or thehandling This implies knowledge o tools,transport o compressors and rerigerant as wellas all relevant rules and saety regulationsI open re or electrical tools are used near thererigerants R600a and R290, this must take placein conormity with current regulationsThe rerigeration systems must always be openedwith a tube cutter

Change rom the rerigerants R12 or R134a toR600a is not permitted, since the rerigerators are not

approved or use with ammable rerigerants, andthe electrical saety has not been tested accordingto current standards. The same applies to changerom the rerigerants R22, R502 or R134a to R290.


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Rerigerant blendsAt the same time as the new environmentallyacceptable rerigerants (R134a and R404A) wereintroduced, some rerigerant blends or servicepurposes were also introduced They were better

environmentally acceptable than the previouslyused CFC rerigerants (R12 and R502)In many countries the rerigerant blends wereonly permitted or a short period, which meantthat they were not widely spread in connectionwith small hermetic rerigeration systemsUse o these rerigerants cannot be recommendedor series production but they can be used orrepair in many cases, see the table on the previouspage

Add inThis designation is used when lling up anexisting rerigeration system with anotherrerigerant than the one originally charged

This is especially the case when problems arisewhich must be solved with as small an operationas possibleCorrespondingly, R22 systems were replenishedwith a small amount o R12 in order to improvethe fow o oil back to the compressorIn several countries it is not allowed to add in onCFC systems (R12, R502, )

1.5Replacement orerigerant(continued)

Drop inThis term means that during service on anexisting rerigeration system ie > 90% o theoriginal mineral oil is poured out and replacedby synthetic oil, and a new suitable lter drier is

mounted Furthermore, the system is chargedwith another compatible rerigerant (ie blend)

RetrotThe term retrot is used about service onrerigeration systems replacing the CFCrerigerant by an environmentally acceptableHFC rerigerantThe rerigeration system is fushed, and thecompressor is replaced by an HFC compressorAlternatively the compressor oil is replaced by asuitable Ester oilThe oil must be changed several times ater shortoperating periods, and the lter drier must bereplaced

In case o oilreplacement a statement romthe compressor manuactorer on materialcompatibility is necessary


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Compressors

2.0Rules or repair work

To enable a hermetic rerigeration system to workas intended and to achieve a reasonable servicelie the content o impurities, moisture and noncondensable gases must be kept on a low levelWhen assembling a new system these

requirements are relatively easy to meet, butwhen repairing a deective rerigeration systemthe matter is more complicated Among otherthings, this is due to the act that aults in a

2.1Opening o the system

rerigeration system oten start disadvantageouschemical processes, and that opening arerigeration system creates possibilities orcontaminationI a repair is to be carried out with a good result

a series o preventive measures is necessaryBeore stating any details about the repair work,some general rules and conditions have to beexplained

Fig. 5: Hermetic rerigeration system with capillary tube

I the rerigeration system contains a fammablererigerant like eg R600a or R290, this will appearrom the type label A Danoss compressor will beprovided with a label as shown in g 6

Fig. 6: Label on compressor or R600a

Service and repair o such systems demandspecially trained personnel This impliesknowledge o tools, transport o compressor andrerigerants as well as the relevant guidelines andsaety rulesWhen working with the rerigerants R600a and

R290 open re may only occur as described inexisting guidelinesFig 7 shows a piercing valve or mounting onthe process tube, thus enabling an opening intothe system or draining o and collecting thererigerant as per instructions

Fig. 8 Recovery unit or rerigerants

Beore starting to cut tubes in the rerigerationsystem it is recommended to clean the tubeswith emery cloth in the places to be cut Thusthe tubes are prepared or the subsequentsoldering, and entry o dirt grains into the systemis avoided

Only use tube cutter, never metal-cutting saw, orcutting tubing in a rerigeration system

Merely a small burr let in the system can cause asubsequent compressor breakdownAll rerigerants must be collected as perinstructions

When a capillary tube is cut it is essential notto admit burrs or deormations to the tube Thecapillary tube can be cut with special pliers (seeg 9), or with a le a trace can be produced in thetube which can then be broken

Fig. 9: Special pliers or capillary tubes

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2.3Filter drier

The lter drier is adsorbing the small wateramounts released through the lie o the systemBesides, it acts as a trap strainer and preventsblocking o the capillary tube inlet and problemswith dirt in the expansion valve

I a rerigeration system has been opened the

lter drier must always be replaced to ensuresucient dryness in the repaired system

Replacement o a lter drier must always bedone without use o a torch When heatingthe lter drier there is a risk o transerring theadsorbed moisture amount to the system, andthe possibility o a fammable rerigerant beingpresent must also be consideredIn case o a non-fammable rerigerant, however,a blowpipe fame may be used but the capillarytube must be broken and then dry nitrogen mustbe blown through the lter towards the open airwhile the lter drier is detachedNormally a lter drier can adsorb a water amount

o approx 10% o the desiccant weight In mostsystems the capacity is not utilized, but in caseso doubt about the lter size it is better to usean oversized lter than one with too small acapacityThe new lter drier must be dry Normally thisis no problem but it must always be ensuredthat the lter drier sealing is intact to preventmoisture collection during storage and transportThe lter drier must be mounted in a way thatfow direction and gravitation have an eect inthe same direction

A system charged with rerigerant must neverbe heated or soldered, especially not when thererigerant is fammableSoldering on a system containing rerigerant willcause ormation o rerigerant decomposition

productsOnce the rerigerant is drained o an inertprotective gas must be lled into the system Thisis done by a thorough blow-through with drynitrogen Beore the blow-through the systemmust be opened in one more place

2.2Brazing under an inertprotective gas

Filter driers with a pore size o 3 ngstrm in

relation to rerigerant:In connection with service on commercialrerigeration systems Danoss DML lters arerecommended

Compressor Filter drier

P and T 6 gram or more

F and N 10 gram or more

SC 15 gram or more

GS 22 gram or more

I the compressor is deective it would beappropriate to cut the suction and pressuretube outside the compressor connectors, notopening the process tubeI, however, the compressor is unctional,

it is recommended to cut the process tubeBlow-through must be done rst throughevaporator and then through condenserAn inlet pressure o approx 5 bar and a blow-through o approx 1-2 minutes would beatisactory on appliances

Thus it is prevented that the Molecular Sieve(MS) balls wear each other and produce dust,which may block the capillary tube inlet Thisvertical position also ensures a quicker pressureequalization in capillary tube systems See g 10

Since water has a molecule size o 28 ngstrm,

molecular sieve lters with a pore size o 3ngstrm are suitable or the normally usedrerigerants, since the water molecules areadsorbed in the pores o the desiccant, whereasthe rerigerant can reely pass through the lter

Fig. 10: Correct location o lter drier

I a lter withaluminium oxide is required or

the suction line, Danoss type DAS burnoutlters or the rerigerants R134a and R404A arerecommended

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Compressors

A repair must always be done quickly, andno rerigeration system must be open to theatmosphere or more than 15 minutes to avoidmoisture intake Thereore it is a good rule tohave all replacement components made ready

beore the system is opened

2.4Moisture penetrationduring repair

Rubber grommets are to be mounted in thecompressor base plate while the compressoris standing on its base plate I the compressoris placed upside down oil will gather in theconnectors, which leads to soldering problemsNever use rubber grommets rom a deectivecompressor since they are oten aged and harderthan new rubber grommetsRemove the cap (Capsolute) rom the processconnector o the new compressor and soldera process tube into the connector Leave thecompressor closed until it is to be soldered into

the systemBesides, it is recommended to plug all connectorson compressor, lter drier and system i or somereason the repair is delayed

The aluminium caps on the connectors must notbe let in the nished system

The caps are only intended to protect thecompressor during storage and transport and donot provide tightness in a system under pressureThe caps make sure that the compressor has notbeen opened ater it let Danoss I the caps aremissing or are damaged, the compressor shouldnot be used until it has been dried and the oil has

been replaced

Never reuse old electrical equipment

It is recommended always to use new electricalequipment with a new compressor, since use oold electrical equipment with a new compressormay lead to the compressor soon developingdeectsThe compressor must not be started without acomplete starting deviceSince part o the starting circuit resistance liesin the starting device, start without completestarting device does not provide good startingtorque and may result in a very quick heating o

the compressor start winding, causing it to bedamaged

The compressor must not be started in vacuum

Start o compressor in vacuum may cause abreakdown inside between the pins o thecurrent lead-in, since the insulation property othe air is reduced at alling pressure

Fig 11 shows a wiring diagram with PTC startingdevice and winding protector A run capacitorconnected to the terminals N and S will reduceenergy consumption on compressors designedor this

2.5Preparation ocompressorand electrical equipment

I it is impossible to complete the repaircontinuously, the open system must be careullysealed o and charged with a slight overpressureo dry nitrogen to avoid moisture penetration

Fig. 11: Wiring diagram with PTC and winding protector

Fig 12 shows a wiring diagram with startingrelay and starting capacitor as well as a motorprotector mounted outside the compressor

Fig. 12: Wiring diagram with starting relay and startingcapacitor

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2.5Preparation o compressorand electrical equipment(continued)

Fig 13 shows a wiring diagram or large SCcompressors with CSR motor

Fig. 13: Wiring diagram or CSR motor

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2.6Soldering

Creation o the correct soldering t is important

Recommended soldering gaps or brazing joints

The connectors o most Danoss compressorsare copperplated steel tubes welded into thecompressor housing, and the welded connections

cannot be damaged by overheating duringsoldering

Please see the section Mounting instructionsor urther details about soldering

Material Material

Solder alloy Copper tubes Steel tubes

Easy-fo 005 - 015 mm 004 - 015 mm

Argo-fo 005 - 025 mm 004 - 02 mm

Sil-os 004 - 02 mm Not suitable


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Compressors

2.7Evacuation

When a rerigeration system is assembled it mustbe careully evacuated (remove air rom thesystem), beore it is charged with rerigerant Thisis necessary to achieve a good repair resultThe main purpose o the evacuation is to reduce

the amount o non-condensable gasses (NCG) inthe system, and secondarily a limited drying willtake placeMoisture in the system may cause ice blocking,reaction with the rerigerant, ageing o theoil, acceleration o oxidation processes andhydrolysis with insulation materialsEvacuation o rerigerating systemNon-condensable gasses (NCG) in a rerigerationsystem may mean increased condensing pressureand thus greater risk o coking processes and ahigher energy consumptionThe content o NCG must be kept below 1 vol %The evacuation may be done in dierent waysdepending on the volume conditions on the

suction and discharge side o the system

I evaporator and compressor have a large volumeone-sided evacuation may be used, otherwisedouble-sided evacuation is recommendedOne-sided evacuation is made through thecompressor process tube but this method

means slightly worse vacuum and slightly highercontent o NCG From the discharge side o thererigeration system the air must be removedthrough the capillary tube, which results in asubstantial restriction The result will be a higherpressure on the discharge side than on thesuction sideThe main actor or the NCG content aterevacuation is the equalized pressure in thesystem, which is determined by the distributiono volumesTypically, the volume on the discharge sidewill constitute 10-20% o the total volume, andthereore the high end pressure has less infuenceon the equalized pressure here than the large

volume and low pressure on the suction side-

Fig. 14: Evacuation process

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2.8Vacuum pump andvacuum gauge

For stationary use a two-stage 20 m3/h vacuumpump can be recommended but or service asmaller two-stage 10 m3/h vacuum pump isbetter suited due to its lower weightA hermetic rerigeration compressor is notsuitable or the purpose since it is not able toproduce a suciently low pressure, and also acompressor used as a vacuum pump would beoverheated and damagedThe insulation resistance o the air is reduced at

alling pressure, and thereore there electricalbreakdown at the current lead-in or in the motoro the hermetic compressor will quickly occur

In order to perorm a sucient evacuation a goodvacuum pump must be available See g 15

Fig. 15: Vacuum pump

The same vacuum pump may be used or alltypes o rerigerants provided that it is chargedwith Ester oilA fameproo vacuum pump must be used orrerigeration systems containing the fammablererigerants R600a and R290

There is no point in having a suitable vacuumpump available i the vacuum obtainedcannot be measured Thereore it is strongly

recommended to use an appropriate robustvacuum gauge (g 16) able to measure pressurebelow 1 mbar

Fig. 16: Vacuum gauge

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To ensure a reasonable rerigeration system liethe rerigerant must have a maximum moisturecontent o max 20 ppm (20 mg/kg)Do not ll rerigerant rom a large container into alling bottle through several container sizes, since

with every drawing-o the water content in thererigerant is increased considerably

Flammable rerigerants R290 and R600aR600a must be stored and transported inapproved containers only and must be handledaccording to existing guidelines

3.0Handling o rerigerants

3.2Maximum rerigerant charge

3.1Charging with rerigerant

I the permissible limit o rerigerant chargestated in the compressor data sheet is exceededthe oil will oam in the compressor ater a coldstart and may result in a damaged valve system inthe compressorThe rerigerant charge must never exceed theamount that can be contained in the condenser

side o the system

Compressor

TypeMax. rerigerant charge

R134a R600a R290 R404A

P 300 g 120 g

T 400 g 150 g 150 g 600 g

TLG 600 g 150 g 150 g

N 400 g 150 g 150 g

F 900 g 150 g 850 g

SC 1300 g 150 g 1300 g

GS 2200 g 2200 g

SC-Twin 2200 g

Do not use open re near the rerigerants R600aand R290The rerigeration systems must be opened with atube cutter

Conversion rom rerigerant R134a to R600ais not permitted, since the rerigerators arenot approved or operation with fammablererigerants, and the electrical saety has notbeen tested according to existing standardseither The same applies to conversion romrerigerant R134a to R290

Normally, charging with rerigerant is no problemwith a suitable charging and provided that theequipment present charging amount o thererigeration system is known See g 17

Fig. 17: Charging board or rerigerant

Always charge the rerigerant amount and

type stated by the rerigerator manuacturerIn most cases this inormation is stated on thererigerator type label The dierent compressorbrands contain dierent amounts o oil, so whenconverting to another brand it may be advisableto correct the amount o rerigerant

Charge o rerigerant can be made by weight orby volume Flammable rerigerants like R600aand R290 must always be charged by weightCharging by volume must be made with arerigerant charging cylinder

The rerigerant R404A and all other rerigerants inthe 400 series must always be charged as liquidI the charging amount is unknown, chargingmust be done gradually until the temperaturedistribution above the evaporator is correctThe rerigerant charge must be made withrunning compressor, rerigerator without loadand with the door closedThe correct charge is characterized by thetemperature rom inlet plus superheat equalsoutlet o the evaporator

Systems with expansion valve must be chargedwith rerigerant until there are no bubbles in thesight glass, which should be placed as close to

the expansion valve as possible

Please also reer to the compressor data sheets,as the present maximum rerigerant charge maydeviate on single types rom the statements inthe ormThe maximum charge o 150 g or R600a andR290 is an upper saety limit o the appliancestandards, whereas the other weights are stated

to avoid liquid hammer

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Compressors

Beore nishing a repair the complete rerigeratormust be tested to make sure that the expectedresult has been achieved It must be ensuredthat the evaporator can be cooled down andthus enable the requested temperatures to be

obtainedFor systems with capillary tube as throttlingdevice it is important to check i the compressorruns satisactorily on the thermostat Further itmust be checked i the thermostat dierential

3.3Test

A hermetic rerigeration system must be tight,and i a rerigerator is to have a reasonablelietime it is necessary to keep any leaks below1 gram rerigerant annuallySince many rerigeration systems with thefammable rerigerants R600a and R290 havecharging amounts below 50 g, in these cases theleaks should be below 05 g rerigerant annually

This requires a high-quality electronical testequipment that can measure these small leakratesIt is relevant to test all soldered joints o thesystem, also in places where no repair has beenmadeThe joints on the discharge side o the system(rom the compressor discharge connector untilcondenser and lter drier) must be examinedduring operation o the compressor, whichresults in the highest pressuresEvaporator, suction tube and compressormust be examined while the compressor isnot operating and the pressure in the systemis equalized, since this results in the highest

pressures here See g 19

3.4Leak test

allows or sucient standstill periods or pressureequalization so an LST compressor (low startingtorque), i any, can start and operate withouttripping on the motor protectorIn areas where undervoltage may occur it is

important to test operating conditions at 85%o the nominal voltage, since both starting andstall torque o the motor will decline when thevoltage is alling

Fig. 19: Leak detector

I no electronic detector (g 19) is available thejoints may be examined with soapy water or withspray, but o course small leaks cannot be oundwith these methods

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In the ollowing a procedure or replacement o adeective compressor in a hermetic rerigerationsystem is outlined, ollowing the undamentalrulesA precondition is that there is a rerigerant

overpressure in the system and that the system isnot contaminated with moisture The rerigerant

4.0Replacement o deectivecompressor

By starting with preparation o the replacementcomponents later delays with opened systemare avoided, and thus also increased risk oradmission o moisture and impuritiesA process tube with process valve must bemounted into the process connector o the newcompressorIn some case it may be an advantage to mounta piece o connecting tube into the compressorsuction connector

4.1Preparation ocomponents

Place a piercing valve with connection to arecovery unit on the compressor process tubePuncture the tube and collect the rerigerantaccording to guidelinesFollow the rules described earlier

4.2Removal o charge

Cut the compressor suction and discharge tubewith a tube cutter approx 25-30 mm rom theconnectors in question, but previously the placesto be cut must be trimmed with emery clothpreparing the solderingI the compressor is to be tested later, the tubeends must be closed with rubber plugs

4.3Removal o deectivecompressor

To avoid decomposition o any rerigerantresidues in the system during the subsequentsoldering operations the system must bethoroughly blown through with dry nitrogen

4.4Removal o rerigerantresidues

The lter drier at the condenser outlet should becut with a tube cutter but another method mayalso be used

4.5Removal o lter drier

Soldering silver must be removed rom the

condenser outlet This is best done by brushing ito while the soldering silver is still liquidThe other tube ends are to be prepared orsoldering in case this was not yet done Take carethat dirt and metal grains are not admitted to thesystem when trimming soldered jointsI necessary, blow through with dry nitrogenwhile trimmingThe new lter drier must be mounted at thecondenser outlet, and the lter must be keptcovered until assembly can take place Avoidheating the lter enclosure itsel with the fameBeore soldering the capillary tube into the ltera slight stop must be produced on the tube asdescribed earlier to ensure the tube end to be at

the right place in the lter to avoid blockingsBe careul during soldering o the capillary tubeand avoid burnings

4.6

Cleaning o solder joints andreassembly

must correspond to the original rerigerantDuring ault nding the compressor is ound tobe deective I it turns out that the motor hasburnt resulting in strong contamination o thesystem another procedure is required

By doing so the later connection o the suctiontube to the compressor can take place urtheraway rom the compressor i mountingconditions in the machine compartment arenarrowWhen the compressor is ready process valve andconnectors must be closed Further, the correctlter drier type must be ready but the cover mustremain intact

To acilitate any analysis or guarantee repair laterthe compressor must be provided with the causeor the ault and the rerigerator production dateCompressors or R600a and R290 must always beevacuated and sealed beore they are returned torerigerator manuacturer or dealer

This is done by connecting the connection tuberom the bottle with dry nitrogen rst to the cutsuction tube and aterwards to the cut dischargetube

Produce a slight fow o dry nitrogen through thedischarge tube to the condenser and maintainthis fow while the lter is careully removed witha torch Avoid heating the lter enclosure itsel

Mount the compressor, which already during

preparation must be provided with rubbergrommetsMount the electrical equipment and connect thewires Evacuation and charge are to be made asdescribed in paragraphs 27 and 31Test to be made as described in paragraphs 33and 34When the process tube is squeezed and solderedthe process valve must be removed


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For systems contaminated with moisture itapplies that the degree o contamination may bevery varying, and the scope o the repair will varyaccordinglySystems containing moisture can be divided

into two categories, namely the ones with a lowdegree o contamination and the ones with ahigh degree o contamination

5.0Systems contaminatedwith moisture

5.1Low degree ocontamination

This deect is usually characterized by the coolingoten being interrupted due to ice blocking in thecapillary tube or in the expansion valve With heatsupply the ice blocking is gradually removed,but i the rerigerant circulates the blocking willquickly build up againThis deect may be due to ollowing reasonsThe system has not been assembled careullyenoughThe components used may have been moist

A rerigerant with too high a moisture contentmay have been usedThe system will oten be new or it has just beenrepaired Usually the moisture amounts aresmall, and thereore the deect can normally beremedied by replacement o rerigerant and lterdrier The procedure is as ollows

a) Open the system at the process tube andcollect the rerigerantIt is an advantage to rst let the compressorrun until it is hot In this way the moisture andrerigerant amount let in the motor or in the

oil is reducedWhen ice is blocking capillary tube or

expansion valve it is possible to run thecompressor hot but the system will not runI capillary tube or expansion valve areaccessible, the place o blocking may be kepthot with a heating lamp or a cloth with hotwater to obtain circulation o the rerigerant

I there is a rupture in a rerigeration system andthe rerigerant overpressure escapes, moisturecontamination will take place The longer timethe system is open to the atmosphere the higherthe degree o contamination I the compressoris operating at the same time, conditions areurther worsened The admitted moisture amount

will distribute in compressor, lter drier and othersystem components depending on their ability tohold the moistureIn the compressor it will especially be the oilcharge that absorbs the water In evaporator,condenser and tubes the contamination willprimarily be determined by the oil amountspresent hereO course the largest water amounts will be incompressor and lter drier There is also a highrisk that valve coking has started damaging thecompressor Thereore compressor and lterdrier must be replaced during the normal repairprocedure

a) Remove the compressor rom the system witha tube cutter

5.2High degree ocontamination

Systems with a low degree o contamination areintact and maintain a rerigerant overpressureSystems with a high degree o contamination,however, are characterized by having been incontact with the atmosphere or moisture has

been added directly The two types o deect willbe treated independently

The evaporating temperature in the systemmay also be increased by heating theevaporator Do not use an open fame orheating

b) Ater collecting the rerigerant the systemmust be blown through with dry nitrogenNitrogen injection must take place throughthe compressor process tube, and rst thesuction side and then the discharge side

must be blown through, rst directing thenitrogen fow rom the compressor throughthe suction tube and evaporator and outthrough the capillary tube, then throughcompressor and condenser and out throughthe lter drier at the condenser outletIt is an advantage to blow through with somuch pressure that any oil in the componentsis removed

c) Replace lter drier and process tube asdescribed earlier It pays to use an oversizedlter drier

d) When the system is reassembled, evacuation

must be carried out very careullyCharge and test according to earliermentioned guidelines

b) Break the capillary tube at the condenseroutlet, and blow through the condenser withdry nitrogen as protective gasRemove the lter drierRepeat the blow-through with increasedpressure to remove oil rom the condenser, iany Cover condenser inlet and outlet

c) Treat suction line heat exchanger andevaporator in the same way The opportunityo an ecient blow-through is improved ithe capillary tube is broken o at theevaporator inlet Blow-through with nitrogenwill then take place in two paces; rst suctiontube and evaporator, then capillary tubesI the reason or the repair is a broken capillarytube the operations must be changed toreplace the entire heat exchanger

d) Reassemble the system with a newcompressor and a new lter drier in the rightsize


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5.3Drying o compressor

In some markets it may be necessary to repair amoist compressor in a workshop, and one is thenobliged to manage somehow

The drying process described here can give thewanted result, provided that the process is closelycomplied withDraw o the compressor oil chargeThen fush the compressor inside with -1 litreso a non-fammable low pressure rerigerant orsolventPlug the compressor with the solvent inside andshake it thoroughly in all directions to get thererigerant in touch with all inside suracesCollect the solvent as stipulatedRepeat the operation once or twice to ensurethat no substantial oil residues are let in thecompressorBlow through the compressor with dry nitrogen

Connect the compressor to an arrangement asshown in g 20

Plug the discharge connector.The connections to the compressor suctionconnector must be vacuum tight This can beachieved by soldered joints or by use o a suitablevacuum hose

In some cases it can be necessary to replenisha compressor with oil i it has lost some o the

chargeOn some Danoss compressors the amount o oilis stated on the type label, however, not on all, sothe present oil type and amount must be oundin the compressor datasheet

5.4Oil charge

5.2High degree ocontamination(continued)

Evacuation must be done with special care,and subsequently charge and test accordingto normal rules The outlined procedure isbest suited or simple rerigeration systemsI the system has dicult access and the

design is complex the ollowing proceduremay be better suited

e) Remove the compressor rom the system andtreat it according to point a

) Break the capillary tube at the condenseroutletBlow through with nitrogen through suctionand discharge tube

g) Mount a new oversized lter drier at thecondenser outlet Connect the capillary tubeto the lter drier

h) When the system, excl compressor, is intact

again carry out a dryingThis is made by at the same time connectingsuction and discharge tube to a vacuum pumpand evacuate to a pressure lower than 10 mbarPressure equalize with dry nitrogenRepeat evacuation and pressure equalization

i) Mount the new compressorThen evacuate, charge and test

Bring the compressor up to a temperaturebetween 115C and 130C beore starting theevacuation Then start the evacuation that must

bring the pressure in the compressor down to 02mbar or lowerThe joints in the vacuum system must be tightin order to achieve the required vacuum Themoisture content in the compressor will alsoinfuence the time or reaching the vacuumI the compressor is highly contaminated a ewpressure equalizations with dry nitrogen toatmospheric pressure will enhance the processShut o the connection to the vacuuminstrument during the pressure equalizationTemperature and vacuum must be maintainedor approx 4 hoursOn nishing the drying process the pressurein the compressor must be equalized to

atmospheric pressure with dry nitrogen and theconnectors must be sealedCharge the compressor with the specied oil typeand amount and mount it into the rerigerationsystem

Fig. 20: Drying o compressor

It is absolutely essential to use the oil approvedor the compressor in question I a lost oil

charge in a compressor must be replaced, it mustgenerally be assumed that approx 50 ccm o theoil charge will be let in the compressor when itis emptied completely by draining oil o rom aconnector

Am0_0140


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6.0Lost rerigerant charge

The term lost charge covers cases where thewanted cooling unction is not achieved becausethere is not sucient amount o rerigerant in thesystemThe repair procedure implies a rerigerant

overpressure in the system so that thecontamination problems that may be caused bypenetrating moisture can be disregardedLost charge is characterized by the act thatthe intended cooling is not achieved Therunning time is long, and the compressor mayrun continuously The build-up o rime on theevaporator is only partly and perhaps onlyaround the injection place The compressor willoperate at low evaporating pressures, and thismeans low power and current consumption Thecompressor will have a higher temperature thannormal due to the reduced rerigerant transportThe dierence between lost charge andblocked capillary tube consists in the prevailing

condenser pressure, however, ater some timethe pressure will be the same in both casesBlocked capillary tube results in the rerigerantbeing pumped into the condenser, and thepressure will become high As the evaporatoris pumped empty, however, the condenser willbecome coldI the blocking is complete no pressureequalization will take place during standstillWith lost charge, however, the pressure in thecondenser will be lower than normalA considerable part o the repair procedureconsists o nding the cause o the deect I thisis not done it will only be a question o time untilthe deect occurs again

In case o blocking o the capillary tube in smallsystems they will normally be scrapped, buti large expensive systems are concerned areplacement o the suction line heat exchangermay be approproate

The main steps in the repair procedure can be asollows (only or non-fammable rerigerants)

a) Mount a service valve on the compressorprocess tube

Mount a pressure gauge and use this or aultdetermination

b) Increase the rerigerant pressure in the systemto 5 bar

c) Examine all joints to see i there is any oiloozing outPerorm a thorough search with leak testequipment until the leak is ound

d) Release the overpressure rom the systemBreak the capillary tube at the condenseroutletBlow through the system with dry nitrogen

e) Replace lter drier as described earlierReplace the process tube and repair the leak

) Evacuate the system and charge it withrerigerantSubsequently make a new leak test and testout the systemAter a pressure test o the system with highpressure perorm a slowly starting evacuationwith a large vacuum pump since otherwisethe oil can be pumped out o the system


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7.0Burnt compressor motor

A burnt motor has destroyed wire insulationBy burning is meant motors where the wireinsulation is decomposed

A real burning is characterized by the wire

insulation in the motor having been exposed tocritical temperatures or a long timeI the temperature conditions in a compressorare changed in a way that the insulation materialassumes a critical temperature or long time aburning will take placeSuch critical conditions may arise when theventilation conditions are reduced (eg due to adeective an), when the condenser is dirty or atabnormal voltage conditionsThe ault lost charge may have a correspondingeect Part o the motor cooling is done bymeans o the circulating rerigerant Whenthe rerigeration system loses charge theevaporating pressure becomes abnormally low,

less rerigerant is circulated per time unit, and thecooling is reducedIn many cases a motor protector mounted in theelectrical equipment cannot protect against suchconditions The motor protector is activated bothby current and by temperature I the currentconsumption is low, a high temperature isrequired around the protector to cause cut-outHowever, at alling evaporating temperatures

7.1Oil acidity

Since a burnt motor may result in contaminationo the system with acid products, the aciditycan be taken as a criterion whether the systemrequires a thorough cleaning

The compressor itsel and the discharge sideo the system up to the lter drier will be th

Compressors DKRCC.pf.000.G3.02 520H6345

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