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NOTE: In order to access the sealed system it will be necessary to install Schrader type fi ttings to the process tubes
on the discharge and suction of the compressor. Proper refrigerant recovery procedures need to be adhered to as
outlined in EPA Regulations. THIS SHOULD ONLY BE ATTEMPTED BY QUALIFIED SERVICE PERSONNEL.
REFRIGERANT CHARGING
NOTE: BECAUSE THE RAC 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 effi ciency.
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 cer tain compressor failures if
they remain uncorrected for any period of time. Quite often,
other problems (such as low air fl ow across evaporator,
etc.) are misdiagnosed as refrigerant charge problems. The
refrigerant circuit diagnosis chart will assist you in properly
diagnosing these systems.
An overcharged unit will at times 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 specifi c
type of failure will be infl uenced 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 suffi cient 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.
METHOD OF CHARGING
The acceptable method for charging the RAC system is the
Weighed in Charge Method. The weighed in charge method
is applicable to all units. It is the preferred method to use, as
it is the most accurate.
The weighed in method should always be used whenever
a charge is removed from a unit such as for a leak repair,
compressor replacement, or when there is no refrigerant
charge left in the unit. To charge by this method, requires
the following steps:
1. Install a piercing valve to remove refrigerant from the
sealed system. (Piercing valve must be removed
from the system before recharging.)
2. Recover Refrigerant in accordance with EPA
regulations.
3. Install a process tube to sealed system.
4. Make necessary repairs to system.
5. Evacuate system to 250 - 300 microns or less.
6. Weigh in refrigerant with the property quantity of
R-22 refrigerant.
7. Start unit, and verify performance.
8. Crimp the process tube and solder the end shut.