SECTION 22: HEATING AND AIR CONDITIONING
DOB 2490-2789 | X3-45 Commuter PA1605 Maintenance Manual (Final Version – Rev.2 April 2016)
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major failure or burnout. A small amount of
refrigerant gas may be discharged. A
characteristic burned odor would also indicate
severe system contamination.
6.8.2 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.
6.8.3 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 using method
described earlier.
5. Circulate clean R-134a or nitrogen using a
pressurized metal cylinder or a reclaiming
machine 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. A/C SYSTEM COMPONENTS
7.1 COMPRESSOR
The A/C compressor is a
Bitzer 4-cylinder
model 4NFCY
. Refer to the “Specifications”
section at the end of this chapter.
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.
2. Remove the radiator fan driving mechanism
belt (Refer to Section 05: Cooling).
3. Slip the old A/C compressor belts off and the
new ones on.
NOTE
Double belts must always be replaced in pairs to
ensure equal distribution of load on each belt.
7.1.2 Belt Tension Adjustment –A/C drive belt
On the mechanical tensioner, slightly loosen
Lock Bolt (A). Adjust tension by turning
Adjustment Screw (B). Tighten the Lock Bolt (A)
to 43 lbf-ft. to preserve adjustment.
