SECTION 22: HEATING AND AIR CONDITIONING
62
PA1621 Maintenance Manual All Series | Section Revised November 2017
WARNING
If discharge pressure is above 100 psig, the
condenser fans will be running. Keep hands
clear of fans
6. Start engine.
7. Switch to fast idle for faster fill and battery
protection.
8. Open the blue gage valve. The suction
pressure should go up meaning the
compressor is sucking from the tank also. If
there is almost no pressure rise, the tank is
too low or too cold.
9. Check the moisture indicator sight glass
and the discharge pressure to meet the
criteria described above.
10. When the sight glass gets clear, you can
add some reserve, up to 2 pounds, as long
as the high pressure does not move up.
11. When finished, close gage valves and
bottle valve.
12. Before stopping the engine, check the
compressor oil level and note it in the repair
book as well as the amount of refrigerant
added.
13. Shut down engine and backseat suction
and discharge shut-off valves (FIGURE 75).
MAX TORQUE: 12 lb-ft (16 Nm)
14. Remove gages and replace caps.
15. Perform a road test for final verification.
6.5.6 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 Central HVAC System nominal charge
requires 24 pounds. If the vehicle is equipped
with the overhead compartment A/C system, a full
charge requires an additional 2 lbs.
After charging the system, it may be necessary to
add refrigerant. Vapor state refrigerant addition
will be done from the suction side of the
compressor while the compressor is in operation.
1. Using connector C24 and C44, energize and
open the liquid solenoid valves (driver’s unit,
passengers’ unit and overhead compartment
units). To do so, uncap and connect male
and female connector housings of C24
together for the passengers’ area (located
on the HVAC module in evaporator
compartment) or C44 for the driver's area
(located on the ceiling of the spare wheel
compartment).
2. Backseat (stem out) the two compressor
shut-off valves (FIGURE 75).
MAX TORQUE: 12 lb-ft (16 Nm)
3. Install A/C pressure gauges at the
compressor shut-off valves service ports
(item 4, FIGURE 75).
4. Midseat the two compressor shut-off valves.
5. Ensure that the two receiver shut-off valves
are in backseated position (stem out).
6. Remove the cover cap from the service port
on the receiver inlet shut-off valve (Figure
42).
7. Attach an evacuated charging hose (purged
from air and moisture) to the R-134a tank.
8. Connect the evacuated charging hose to the
service port on the receiver tank inlet shut-
off valve.
9. Open the R-134a tank valve. The refrigerant
supply tank should be kept warm to allow
more refrigerant to be transferred into the
system. Use a heating blanket for this
matter.
10. Midseat the receiver inlet shut-off valve. The
R-134a will now enter the system.
11. The proper charge of R-134a is 24 lbs, to
this, add 2 lbs for overhead compartments
A/C system. When the scale indicates this
amount of charge, backseat the receiver
valve and close the R-134a tank valve.
12. Disconnect the charging hose. Replace the
cover caps.
13. Disconnect C24 & C44.
14. The system is now ready for operation.
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