Section 22: HEATING AND AIR CONDITIONING
PA1562
18
10. After the second “sweep”, change the filter
drier (if you have not done so) and
evacuate to 500 microns.
11. Evacuating the system below 500 microns
on systems using the Carrier 05G
compressor may risk drawing air into the
system past the carbon shaft seal.
12. Check to insure that vacuum holds. (If the
pressure continues to rise, it indicates a
leak or moisture in the system).
13. Charge the system with the proper amount
of refrigerant using recommended charging
procedures.
NOTE
This method will aid in preventing
unnecessary system failures by ensuring that
the refrigeration system is free of
contaminants.
6.6 CHARGING SYSTEM
When a system has been opened or if there are
any questions about the air or moisture in the
system, evacuate the system. Charging of an
evacuated system may be accomplished by
forcing liquid R-134a directly into the receiver
tank. This may be accomplished by placing the
refrigerant cylinder upside down on a scale with
the valves at the bottom. This ensures that only
liquid will enter the receiver tank.
When charging an empty system, weigh the
amount of refrigerant put into the system. This
will eliminate any possibility of overfilling. A
nominal charge requires 24 pounds (10,9 kg). If
the vehicle is equipped with an auxiliary system, a
full charge requires 5.6 lbs (2,6 kg).
1. Backseat the two compressor shutoff valves
("out").
2. Install the test gauges at the shutoff valves
noting that the 400 psi (2758 kPa) gauge is
connected to the discharge.
3. Turn in the two shutoff valves 3 to 4 turns.
4. Open the lower receiver valve by turning
“out” all the way.
5. Backseat the upper receiver valve by turning
out all the way.
6. Remove the cover cap from the service
fitting in the top receiver valve.
7. Attach a charging hose to the R-134a tank.
Open the tank valve slightly permitting R-
134a to escape thus purging the hose of air.
8. Connect the charging hose to the service
fitting.
9. Open the R-134a tank valve.
10. To build up pressure in the receiver tank,
heat the receiver tank with a heating
blanket.
11. Turn in the upper receiver valve several
turns. The R-134a will now enter the
system.
12. The proper charge of R-134a is 24 lbs
(10.89 kg). When the scale indicates this
amount of charge, backseat the receiver
valve and close the R-134a tank valve.
13. Disconnect the charging hose. Replace the
cover caps.
14. The system is now ready for operation.
CAUTION
The evacuation of the system must be made
by authorized and qualified personnel only.
Refer to local laws for R-134a recuperation.
6.7 REFRIGERANT SYSTEM CLEAN-OUT
AFTER COMPRESSOR FAILURE
Although the vast majority of reciprocating
refrigerant compressors manufactured today are
extremely reliable, a small percentage do fail.
These failures usually result in minor or
extensive system contamination depending on
the severity of the failure. When an open type
compressor becomes damaged internally, this
provokes small particles of bearings, steel,
brass, copper, and aluminum and, in severe
cases, carbonized oil, which could contaminate
the system. To prevent repeated failures, the
problem which caused the failure should be
corrected, and depending upon the severity of
the failure, the system should be thoroughly
cleaned out using one of the clean-out
procedures mentioned.
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