SECTION 22: HEATING AND AIR CONDITIONING
24
DOB 2490-2789 | X3-45 Commuter PA1605 Maintenance Manual (Final Version – Rev.2 April 2016)
book as well as the amount of refrigerant
added.
13. Shut down engine and backseat suction
and discharge shut-off valves (FIGURE 20).
14. Remove gages and replace caps.
15. Perform a road test for final verification.
6.7 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 plus an
additional 2 lbs for parcel rack A/C system
.
After charging the system, it may be necessary to
add refrigerant. Vapor state refrigerant will be
done from the suction side of the compressor
while the compressor is in operation. Refer to 6.6
Adding Vapor State Refrigerant
1. Using connector C24 and C44, energize and
open the liquid solenoid valves (driver’s unit,
passengers’ unit and parcel rack 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 20).
3. Install A/C pressure gauges at the
compressor shut-off valves service ports
(item 4, FIGURE 20).
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
36).
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 parcel racks 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.
6.8 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.
6.8.1 Determining Severity of Failure
The severity of compressor failure can be
categorized as minor or major. A failure is
considered minor when the contamination is
limited to the compressor with little or no system
contamination. A major failure, or burnout,
results in extensive system contamination as
well as compressor damage. Extensive system
contamination can be determined by
withdrawing a small sample of compressor oil
and checking its color, odor and acidity. A
Virginia Chemical "TKO" one step acid test kit is
one of several compressor oil test kits that may
be used. A high acid content would indicate a
