Service manual

19
Service Information
Verify Refrigerant Type In The
System
Forexample,hosesthatwereusedfora
refrigerationsystemoperatingonR-12maycontain
smallquantitiesofmineraloilwhichcanblockthe
capillarytubeinasystemoperatingonR-134a.As
littleasonemilligrammaybesufcienttocausea
blockage.Inaddition,sealedsystemcomponents
thathavebeenusedwithCFCsystemsmustnot
beusedwithR-134asystems.Thesecomponents
maycontainresidualamountsofrefrigerantandoil
whichcoulddamageanR-134asystem.
NOTICE
Instructionsgivenherearefurnishedasaguide.
Personsattemptingtousetheseinstructionsto
makerepairstothesealedrefrigerationsystem
shouldhaveaworkingknowledgeofrefrigeration
andprevioustrainingonsealedsystemrepair.
CAUTION
R-134a and R-12 are completely incompatible.
Before starting any sealed system repair, it is
extremely important to check serial plate of
product to verify the type of refrigerant in the
system.
Dedicated Equipment
R-134amustnotbemixedwithothertypes
ofrefrigerants.R-134amustberecoveredin
dedicatedandproperlyidentiedrecoverybags
andtanks.
Itwillbenecessarytocheckwiththemanufacturer
ofyourrecoveryequipmenttodetermine
R-134acompatibility.Somerecoveryequipment
manufacturershavechangeoverinstructions
forswitchingbetweenrefrigeranttypes.Protect
yourselfandyourequipmentbyfollowingall
manufacturerguidelines.
Also,ensurethatyourrefrigerationhoses
arespeciedforusewithR-134arefrigerant.
Researchhasshownthatcompoundsinstandard
refrigerationhosesmayentersealedsystems
andultimatelyrestrictthecaptubeinanR-134a
system.
R-134a Refrigeration Systems
Thesealedrefrigerationsystemwillconsistofthe
samebasiccomponentsbeingutilizedintheR-12
systems.
Thereisa10%to15%dischargepressure
increaseusingR-134a,witha5%to10%decrease
insuctionpressurewhencomparedtothesame
productwithanR-12systemoperatingat90°F
(32°C)ambienttemperatureconditions.Lower
suctionpressuresresultfromthelowerdensityof
R-134arefrigerantwhicheffectsrefrigerantow
rate.R-134asystemscommonlyoperateina1”-2”
vacuumonthesuctionside.
ProductsusingR-134arefrigerantwillgenerally
havealongercapillarytubetomaintainasimilar
owrateandsomemodelswillhavealarger
condensertoreducethedischargepressuresand
lowerstart-upsoundtransmission.
Miscibility of R-134a and
Ester Oil
AspecialsyntheticoilknownasEsteroilisused
asalubricantinrefrigerationsystemsoperating
onR-134a.Esteroilsareproducedfromalcohols
andfattyacidsandareavailableinseveral
differentvariants.Esteroilshaveapleasantaroma
reminiscentoffruit.
Esteroilsgenerallyincludevarioustypesof
additivesforimprovingcertainpropertiessuch
asviscosity,temperaturesensitivity,etc.These
additivesareoftenaggressive,andskincontact
withEsteroilsshouldthereforebeavoided.
Oneofthemostimportantrequirementsmade
onarefrigerantsystemisthattheoilmixwiththe
refrigerant.Sincemineraloilandordinarysynthetic
oilDONOTmixwithR-134a,Esteroilisusedfor
lubrication.EsteroildissolvesinR-134a.
Esteroilisbrokendownbychlorineandcannot
beusedwithR-12(R-12containschlorine)orany
othercompoundcontainingchlorine.Therefore,
R-134arefrigerationsystemshavevirtually
notoleranceforchlorinemoleculesfromCFC
refrigerants(R-134aisanHFCandcontainsno
chlorine).
CAUTION
During R-134a service, it is extremely
important to avoid using equipment that may
contain residual amounts of mineral oil, CFC’s
or HCFC’s which could enter and contaminate
the sealed system.