44 PB
R-410A SEALED SYSTEM REPAIRS
WARNING
RISK OF ELECTRIC SHOCK
Unplug and/or disconnect all electrical power
to the unit before performing inspections,
maintenances or service.
Failure to do so could result in electric shock,
serious injury or death.
WARNING
HIGH PRESSURE HAZARD
Sealed Refrigeration System contains refrigerant
and oil under high pressure.
Proper safety procedures must be followed,
and proper protective clothing must be worn
when working with refrigerants.
Failure to follow these procedures could
result in serious injury or death.
Undercharged Refrigerant Systems
Anunderchargedsystemwillresultinpoor
performance(lowpressures,etc.)inboththeheating
andcoolingcycle.
Wheneveryouserviceaunitwithanunderchargeof
refrigerant,alwayssuspectaleak.Theleakmustbe
repairedbeforechargingtheunit.
Tocheckforanunderchargedsystem,turntheuniton,
allowthecompressortorunlongenoughtoestablish
workingpressuresinthesystem(15to20minutes).
Duringthecoolingcycleyoucanlistencarefullyat
theexitofthemeteringdeviceintotheevaporator;an
intermittenthissingandgurglingsoundindicatesalow
refrigerantcharge.Intermittentfrostingandthawing
oftheevaporatorisanotherindicationofalowcharge,
however,frostingandthawingcanalsobecausedby
insufcientairovertheevaporator.
Checksforanunderchargedsystemcanbemadeat
thecompressor.Ifthecompressorseemsquieterthan
normal,itisanindicationofalowrefrigerantcharge.
Acheckoftheamperagedrawnbythecompressor
motorshouldshowalowerreading.(ChecktheUnit
Specication.)Aftertheunithasrun10to15minutes,
checkthegaugepressures.Gaugesconnectedto
systemwithanunderchargewillhavelowhead
pressuresandsubstantiallylowsuctionpressures.
Figure 601 (Undercharged System)