PREVOST LE MIRAGE XLII BUS SHELLS, Maintenance Manual

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Section 22: HEATING AND AIR CONDITIONING
PA1564
37
10.2.2 When the compressor is inoperable
* Evacuate the system (Refer to paragraph
10.2.3).
*
Slacken bolts A (Refer to figure 38).
* Remove bolts B & C (Refer to figure 38).
* Remove the compressor.
FIGURE 38: COMPRESSOR REMOVAL OR
INSTALLATION
22349
10.2.3 Evacuating System Before Adding
Refrigerant (Small HVAC System)
When a system has been opened for repairs,
change the filter dryer and evacuate the system.
XLII vehicles equipped with a small HVAC
system must use high-pressure service port
located on the other side of check valve and
low-pressure port located alongside rear truss
(Fig. 39). It would be good practice to open
solenoid valve.
1. Connect two hoses equipped with a micron
gauge between the high-pressure service
port, the low-pressure service port and the
vacuum pump.
2. With the unit service valves open and the
vacuum pump valves open, start the pump
and draw the manifold and hoses into a
very deep vacuum (700 microns).
3. Close manifold valve
4. Shut down the vacuum pump.
5. Check to insure that vacuum holds. (If the
pressure continues to rise, it indicates a
leak or moisture in the system).
6. Charge the system with the proper amount
of refrigerant through the service port near
the check valve using recommended
charging procedures.
7. Remove the hoses.
10.3 OIL ADDITION
The chart below shows the approximate amount
of oil to be added to the system when replacing
a component.
Component replaced Typical amount of oil
Evaporator
Condenser
Filter-Dryer
50 cm³ (1.7 ozs)
30 cm³ (1.0 ozs)
10 cm³ (0.3 ozs)
The amount of oil recovered with the refrigerant
recovery should be added at the same time.
10.4 COMPRESSOR OIL CONTAMINATION
Unlike engine oil, no cleaning agent is added to
the compressor oil. Even if the compressor is
run for a long time, the oil never becomes turbid
as long as there is nothing wrong with the
compressor or its method of use. Inspect the
extracted oil for any of the following conditions:
* Dirt in the oil.
*
Change to a varnish color.
* Presence of foreign substance, metal
shavings, etc. in the oil. When the oil
extracted from the compressor is as
described above, replace the oil as follows:
1. Clean the interior of the system with
approved method.
2. Replace the filter-dryer.
3. Supply with new oil as specified in
SANDEN SD Compressor Service
Manual included at the end of this section.
10.5 OIL RETURN OPERATION
There is a close affinity between oil and
refrigerant. During normal operation, part of the
oil recirculates with the refrigerant in the system.
Therefore, when checking the amount of oil in
the system or replacing any system component,
the compressor must be run in advance to
ensure return. This procedure is as follows:
* If the amount of refrigerant in the system has
decreased, charge to the proper amount.
* Start the engine and select fast idle.
* Set the fan speed to full air/full A/C and let
run for 20 minutes.