Refrigeration Service Operations
103
Compressor Oil Filter
This unit is equipped with a compressor oil filter.
The compressor oil filter should be changed when
the drier is replaced.
The outlet fitting is larger than the inlet fitting, so
the compressor oil filter cannot be put on
backwards. There are two fittings on the inlet end
of the compressor oil filter. The inlet fitting
contains a check valve that prevents reverse flow
through the compressor oil filter. The capped
fitting is called the oil pressure access port and is
used to check the compressor oil pressure (see
“Checking Compressor Oil Pressure” on
page 103).
Use the following procedure to change the
compressor oil filter.
1. Pump down the low side and equalize the
pressure to slightly positive.
2. Front seat the discharge and suction service
valves. Remove the remaining refrigerant
from the compressor.
3. Disconnect the oil lines from the compressor
oil filter. Hold the oil filter with back-up
wrench on the hex behind the ORS fitting.
4. Remove the clamp and the compressor oil
filter.
5. Coat the new O-rings with clean compressor
oil and place them in the ORS fittings on the
ends of the new compressor oil filter.
6. Fasten the new compressor oil filter in place
with the clamp.
7. Attach and tighten the oil lines to the
compressor oil filter. Hold the oil filter with a
back-up wrench on the hex behind the ORS
fitting.
8. Evacuate the compressor and filter to a
maximum of 500 microns to remove trapped
air.
9. Open the service valves, operate the system,
and check the compressor oil filter for leaks.
Checking Compressor Oil
Pressure
The oil pressure at the oil pressure access port
varies with the suction pressure in the compressor.
Therefore, we need to calculate the “net oil
pressure” to determine the actual compressor oil
pressure. The net oil pressure is the pressure at the
oil pressure access port minus the suction pressure
below the throttling valve. Use the following
procedure to check the compressor oil pressure.
1. Attach a suitable oil pressure gauge to the oil
pressure access port on the compressor oil
filter.
1. Oil Pressure Access Port
2. Inlet Fitting
3. Outlet Fitting
Figure 70: Compressor Oil Filter
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AEA718
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