Section 22: HEATING AND AIR CONDITIONING
PA1562
19
6.7.1 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.
6.7.2 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.
6.7.3 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.
5. Circulate clean R-134a or nitrogen 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
filter dryer again and replace the moisture-
liquid indicator.
9. After approximately 7 days of operation,
recheck the compressor oil for cleanliness
and acidity.
7. CENTRAL A/C SYSTEM COMPONENTS
7.1 COMPRESSOR (CENTRAL SYSTEM)
7.1.1 Belt Replacement
DANGER
Set the battery master switch to the “Off”
position. For greater safety, set the engine
starter selector switch in engine compartment
to the “Off” position.
1. Open engine compartment rear doors and
locate the belt tensioner pressure releasing
valve (Fig. 18), mounted above the engine
R.H. side door next to the air pressure
regulator, then turn handle clockwise in
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