Friedrich VERT-I-PAK VHA-18K75RTP, Service & Parts Manual

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31 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.
Refrigerant Charging
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 efficiency. 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.
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 flow 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 specific type of failure will be influenced 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 sufficient 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.