True DRY DH1 50
15 69-2271EFS—01
Replacing a Burned Out Compressor
Therefrigerantandoilmixtureinacompressorischemicallyvery stableundernormaloperatingconditions.
However,whenanelectricalshortoccursinthecompressormotor,theresultinghightemperaturearccausesapor-
tionoftherefrigerantoilmixturetobreakdownintocarbonaceous sludge,averycorrosiveacid,andwater.These
contaminantsmustbecarefullyremovedotherwiseevensmallresidueswillattack replacementcompressormotors
and cause failures.
Thefollowingprocedureiseffectiveonlyifthesystemismonitoredafter replacingthecompressortoinsurethatthe
clean up was complete.
1. Thisprocedureassumesthatthepreviouslylistedcompressormotorcircuittestsrevealeda shortedoropen
winding.
2. Removeandproperlydisposeofthesystemcharge.DONOT venttherefrigerantorallowittocontactyoureyes
orskin.
3. Removetheburnedoutcompressor.Userubberglovesifthereisanypossibility ofcontactingtheoilorsludge.
4. Tofacilitatesubsequentsteps,determinethetypeofburnoutthatoccurred.If thedischargelineshowsno
evidenceofsludgeandthesuctionlineisalso cleanorperhapshassomelightcarbondeposits,the burnout
occurred while the compressor was not rotating. Contaminants are therefore largely confined to the compressor
housing.Asingleinstallationofliquidandsuctionline filter/drierswillprobablycleanupthesystem.
Ifsludgeisevidentinthedischargeline,it willlikelybefoundinthesuctionline.Thisindicates thecompressor
burnedoutwillrunning.Sludgeandacidhavebeen pumpedthroughoutthesystem.Severalchangesoftheliquid
andsuctionfilter/drierswillprobablybenecessarytocleansethe system.
5. Correctthesystemfaultthatcausedtheburnout. Consultthefactoryforadvice.
6. Installthereplacementcompressorwithanewcapacitorandanoversized liquidlinefilter.
Inarunningburnout,installanoversizedsuction linefilter/drierbetweentheaccumulatorandcompressor.
Thoroughlyflushtheaccumulatorwithrefrigeranttoremovealltrappedsludge andtopreventtheoilholefrom
becomingplugged.Astandingburnoutdoesnotrequirea suctionlinefilter/drier.
7. Evacuatethesystemwithagoodvacuumpumpand accuratevacuumgauge.Leavethepumponthesystem
for at least an hour.
8. Operatethesystemforashortperiodoftime, monitoringthesuctionpressuretodeterminethatthesuction
filterisnotbecomingplugged.Replacethesuctionfilter/drier ifpressuredropoccurs.Ifasevererunningburn
outhasoccurred,severalfilter/driersmayhavetobereplacedto removealloftheacidandmoisture.
NOTE:NEVERusethecompressortoevacuatethesystemor anypartofit.
Replacing a Compressor, Non-Burnout
Removetherefrigerantfromthesystem.Replacethecompressorandliquid linefilter/drier.Chargethesystemto50
PSIGandcheckforleaks.Removethechargeandweigh intherefrigerantquantitylistedonthenameplate.Operate
the system to verify performance.
Defrost Thermostat
Thedefrostthermostatisattachedtotherefrigerantsuctiontubebetween theaccumulatorandthecompressor.It
willautomaticallyshutthecompressoroffifthelowsiderefrigerant temperaturedropsduetoexcessivefrostfor-
mationontheevaporatorcoil.Theimpellerfanwill continuetorun,causingairtoflowthroughtheevaporator coil
andmelttheice.Whentheicehasmelted, theevaporatortemperaturewillriseandthethermostatwillrestartthe
compressor.
Troubleshooting