Isuzu N-Series. Manual - part 68
1D1-4 COMPRESSOR OVERHAUL EXCEPT TAIWAN
Checking and Adjusting for Compressor Replace-
ment
180 cc (5.0 lmp fl oz) of oil is charged in compressor
(service parts). So it is necessary to drain the proper
amount of oil from the new compressor.
1. Perform oil return operation.
2. Discharge refrigerant and remove the compressor.
3. Drain the compressor oil and measure the extract-
ed oil.
4. Check the compressor oil for contamination.
5. Adjust oil level as required.
6. Evacuate, charge and perform oil return operation.
7. Check system operation.
Contamination of compressor oil
Unlike engine oil, no cleaning agent is added to the com-
pressor oil. Even if the compressor runs for a long period
of time (approximately 1 season), the oil never becomes
contaminated 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:
• The capacity of the oil has increased.
• The oil has changed color to red.
• Foreign substances, metal powder, etc., are
present in the oil.
If any of these conditions exists, compressor oil is
contaminated. Whenever contaminated compressor
oil is discovered, the receiver/drier must be re-
placed.
Oil return operation
There is close affinity between the oil and the refriger-
ant. During normal operation, part of the oil recirculates
with the refrigerant in the system.
When checking the amount of oil in the system, or re-
placing any component of the system, the compressor
must be run in advance for oil return operation. The pro-
cedure is as follows:
1. Open the all doors and engine hood.
2. Start the engine and A/C switch is “ON”. Set the fan
control knob at its highest position.
3. Run the compressor for more than 20 minutes be-
tween 800 and 1,000 rpm in order to operate the
system.
4. Stop the engine.
Replacement of component parts
When replacing system component parts, supply the fol-
lowing amount of oil to the component parts to be in-
stalled.
Amount of oil drained
from used compressor
Draining amount of oil
from new compressor
less than 180 cc
(3.4 Imp fl oz)
Same as drained amount
more than 180 cc
(3.4 Imp fl oz)
180 cc (3.4 lmp fl oz)
Component parts to be installed
Amount of oil
Evaporator
50 cc (1.4 lmp fl oz)
Condenser
30 cc (0.8 Imp fl oz)
Receiver/drier
30 cc (0.8 Imp fl oz)
Refrigerant line (One piece)
10 cc (0.3 Imp fl oz)
N1A0141E