49 PB
R-410A SEALED SYSTEM REPAIRS
Refrigerant Charging
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.
NOTE: Always weigh in refrigerant based on the model nameplate.
NOTE: Because the refrigerant system is a sealed system, service process tubes will have to be installed. First install a line tap
and remove refrigerant from system. Make necessary sealed system repairs and vacuum system. Crimp process tube line and
solder end shut. Do not leave a service valve in the sealed system.
Proper refrigerant charge is essential to proper unit operation. Operating a unit with an improper refrigerant charge will result
in reduced performance (capacity) and/or efciency. Accordingly, the use of proper charging methods during servicing will
insure that the unit is functioning as designed and that its compressor will not be damaged.
NOTE:Factory sealed units will not be overcharged
Too much refrigerant (overcharge) in the system is just as bad (if not worse) than not enough refrigerant (undercharge). they
both can be the source of certain compressor failures if they remain uncorrected for any period of time. Quite often, other
problems (such as low air ow across evaporator, etc.) are misdiagnosed as refrigerant charge problems. The refrigerant
circuit diagnosis chart will assist you in properly diagnosing the systems.
An overcharged unit will return liquid refrigerant (slugging) back to the suction side of the compressor eventually causing a
mechanical failure within the compressor. This mechanical failure can manifest itself as valve failure, bearing failure, and/or
other mechanical failure. The specic type of failure will be inuenced by the amount of liquid being returned, and the length of
time the slugging continues.
Not enough refrigerant (undercharge) on the other hand, will cause the temperature of the suction gas to increase to the point
where it does not provide sufcient cooling for the compressor motor. When this occurs, the motor winding temperature will
increase causing the motor to overheat and possibly cycle open the compressor overload protector. Continued overheating of
the motor windings and/or cycling of the overload will eventually lead to compressor motor or overload failure.
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