SECTION 22: HEATING AND AIR CONDITIONING
DOB 1300-1556 | X3-45 Commuter PA-1648 Maintenance Manual First release Oct 2020
the recommended torque. The O-rings are
designed to seal at the specified torque and
overtightening the connection does not
result in a satisfactory and permanently
sealed connection. The connection must be
disassembled and the cause of the leak
(damaged O-ring, defective lines, etc.)
corrected. Use new O-ring.
6.7.3 Refrigerant System Clean-out After
Compressor Failure
Although the vast majority of reciprocating
refrigerant compressors manufactured today are
extremely reliable, a small percentage do fail.
These failures usually result in minor or
extensive system contamination depending on
the severity of the failure. When an open type
compressor becomes damaged internally, this
provokes small particles of bearings, steel,
brass, copper, and aluminum and, in severe
cases, carbonized oil, which could contaminate
the system. To prevent repeated failures, the
problem which caused the failure should be
corrected, and depending upon the severity of
the failure, the system should be thoroughly
cleaned out using one of the clean-out
procedures mentioned.
Determining Severity of Failure
The severity of compressor failure can be
categorized as minor or major. A failure is
considered minor when the contamination is
limited to the compressor with little or no system
contamination. A major failure, or burnout,
results in extensive system contamination as
well as compressor damage. Extensive system
contamination can be determined by
withdrawing a small sample of compressor oil
and checking its color, odor and acidity. A
Virginia Chemical "TKO" one step acid test kit is
one of several compressor oil test kits that may
be used. A high acid content would indicate a
major failure or burnout. A small amount of
refrigerant gas may be discharged. A
characteristic burned odor would also indicate
severe system contamination.
Clean-out after Minor Compressor Failure
1. Be sure to correct the problem which
caused the failure.
2. Change liquid line filter dryer.
3. Run the unit for 2 hours on high speed cool
only.
4. Check compressor oil level to ensure
compressor is not overcharged with oil.
Sometimes a significant amount of oil is
pumped out of the compressor to other
parts of the system when a compressor
fails. This oil will return to the replacement
compressor when it is started, causing an
overcharge of oil in the sump of the
replacement compressor. In this case, it is
important that the oil level be adjusted to
the proper level.
5. Withdraw a sample of the compressor oil and
check its color, odor, and acidity, using
instructions supplied above. If the oil is
contaminated, change the oil and filter dryer,
and repeat the procedure until the system is
clean.
Clean-out After Major Compressor Failure
1. Reclaim the refrigerant into a refrigerant
bottle through a filter dryer to filter out
contaminants.
2. Remove the failed compressor and repair it if
possible.
3. Install new or repaired compressor.
4. Change the filter dryer using prescribed
method.
5. Circulate clean R-134a with the reclaimer to
clean out many of the contaminants collected
in the coil valves, TXV (Thermal Expansion
Valve), solenoid valves, check valves, and
any other mechanical component that may
have collected contaminants.
6. Evacuate and charge the system normally.
7. Run the unit for 8 hours and monitor the
pressure drop across the filter dryer. Also
check the liquid line dryer for signs of
restriction. If the pressure drop across the
filter dryer exceeds 12 to 14 psig (82,75 to
96,5 kPa) with a 40°F (5°C) evaporator coil
temperature, stop the unit and change the
liquid line and suction line filter dryer. After 4
or 5 hours of operation stop the unit and
replace the filter dryer.
8. After 8 hours of operation stop the unit and
remove a sample of the compressor oil and
check its color, odor, and acidity, using
instructions supplied above. If the oil is
contaminated, replace the oil and repeat step
7. If the oil is not contaminated, change the
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