Filter-Dryer; Refrigerant Recovery; Evacuating System Prior Addition Of Refrigerant (Driver's Or Auxiliary System); Oil Addition - PREVOST H3-41 Maintenance Manual

7.5

REFRIGERANT RECOVERY

The release of refrigerant into the atmosphere
must be avoided. Whenever refrigerant is to be
released from the air-conditioning system, a
refrigerant recovery unit must be used to recover
the refrigerant. This refrigerant can then be
recycled and reused,
environmentally safe and economical.
For complete system recovery, any of the High
and Low service ports can be used. Energize
liquid solenoid valve and measure the quantity
of oil recovered. For the compressor only, use
the service valve port and close the valves. The
service valves open permits full flow of
refrigerant to service port. Service valve closed
permits flow of refrigerant from compressor to
service port.
7.6 EVACUATING SYSTEM PRIOR
ADDITION OF REFRIGERANT
(DRIVER'S OR AUXILIARY SYSTEM)
When a system has been opened for repairs,
change the filter-dryer and evacuate the system.
Use the high-pressure service port and low-
pressure port. It would be good practice to open
the 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
charging procedures.
7. Remove the hoses.
which is both
using recommended
PA1621 Maintenance Manual All Series | Revised February 2019
SECTION 22: HEATING AND AIR CONDITIONING
7.7

OIL ADDITION

The chart below shows the approximate amount
of oil to be added to the system when replacing
a component.
Component replaced
Evaporator
Condenser

Filter-Dryer

The amount of oil recovered with the refrigerant
recovery should be added at the same time.
7.8

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
shavings, etc. in the oil. When the oil
extracted from
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 small
compressor service manual.
7.9

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.
Typical amount of oil
50 ml (1.7 ozs)
30 ml (1.0 ozs)
10 ml (0.3 ozs)
foreign substance,
the compressor is
71
metal
as