SECTION 22: HEATING AND AIR CONDITIONING
22
DOB 2490-2789 | X3-45 Commuter PA1605 Maintenance Manual (Final Version – Rev.2 April 2016)
FIGURE 22: RECOVERY UNIT CONNECTED TO
RECEIVER SERVICE PORT
5. Perform the recovery of the refrigerant as
prescribed by the recovery unit
manufacturer.
6.5 EVACUATING
SYSTEM
When A/C system has been opened or if there
are any questions about the air or moisture in
the system, evacuate the system.
Backseat (stem out) both compressor shut-off
valves. Evacuate the entire system including
compressor using a
vacuum pump
connected
to the high and low pressure sides.
A steady vacuum (i.e. pressure does not rise
within two hours) less than 0.02 psi (1.5 mbar)
must be maintained once the vacuum pump is
turned off.
CAUTION
The evacuation of the system must be made
by authorized and qualified personnel only.
Refer to local laws for R-134a recuperation.
1. Make sure both receiver tank shut-off
valves are is the normal backseated
position (stem turned out).
2. Clean the area around the compressor
shut-off valves.
3. Remove the blue and red caps from the
service ports on suction and discharge shut-
off valves. Connect two hoses to the
vacuum pump.
4. Meadseat the compressor suction and
discharge shut-off valves.
5. 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).
6. Start the vacuum pump.
7. The pressure will drop to approximately 29
in-HG gauge vacuum.
8. Evacuate to a system pressure of 500
micron.
9. Shut down the vacuum pump. Validate that
the vacuum holds. If the pressure rises, it
indicates a leak.
10. Backseat the compressor shut-off valves by
turning “out” all the way.
11. Remove the hoses.
12. Reinstall the red and blue caps at the
suction and discharge shut-off valves
service ports.
13. Disconnect C24 & C44.
6.6 ADDING VAPOR STATE REFRIGERANT
Addition of vapor state refrigerant is carried-out
to compensate for hose permeation and shaft
seal losses over a long period and is done from
the suction side while compressor is in
operation.
A typical sign of refrigerant low charge would be
A/C lower performance experienced by the user.
Perform the usual leak inspection and correct
any leaks before adding refrigerant.
6.6.1 Verification
Perform the following verifications:
1- A vehicle stopped for more than 4 hours
should show the lower receiver tank sight
glass full at room temperature or with some
level if ambient temperature is high. This
method is less accurate when ambient
temperature gets high.
2- With the AC on for at least 10 minutes, the
moisture indicator sight glass (FIGURE 23)
should be clear, not milky, without bubbles
in the stream of refrigerant. Bubbles in the
moisture indicator sight glass are sign of
refrigerant low charge. The filter-dryer
nearby should be near constant
temperature, less than 5°F differential
between inlet and outlet. A partially blocked
filter will make some flash gas and give a
“milky” sight glass.
