TM 9-2320-387-24-2
Table 14-3. Air Conditioning
Doubleshooting
(Cont’d).
I MALFUNCTION
TEST OR INSPECTION
I
2.
INTERMITENT
COOLING
Check air conditioner output for temperature variation. If air is intermittently warm and cold, perform
the following:
Step 1.
Check for air or moisture in system by performing malfunction lb.
Step 2.
Ensure temperature sensing probe is inserted properly in the evaporator fins near the
outlet (para. 25-26).
Step 3.
Perform mechanical troubleshooting, malfunction 9.
step 4.
Check sight glass reading for oil streaks indicating too much oil in system.
Step 5.
If there is excess oil in system, flush A/C system (para. 25-15). Charge A/C system with
correct quantity of refrigerant oil (para. 25-15).
END OF TESTING!
AIR CONDITIONER COMPRESSOR
NOTE
Before beginning compressor troubleshooting or inspection procedures,
always clean away oil, grease, dirt, and refrigerant residue.
3. INSUFFICIENT COOLING
a. If air conditioner compressor runs smoothly, perform the following:
Step 1.
Step 2.
Step 3.
Step 4.
Step 5.
Step 6.
Connect manifold gauge set to low and high service connector ports (para. 25-15).
Run compressor at idle speed (1,500 rpm) for five minutes.
If-unusually high low pressure is observed in combination with unusually low high side
pressure, stop compressor and measure elapsed time before high side pressure is equal to
low side pressure. If less than two minutes, then reed valve or head gasket may be
defective. Replace compressor (para. 25-20).
If unusually low side pressure and high side pressure are observed, check for low
refrigerant charge or refrigerant leaks and replenish refrigerant as necessary
(para. 25-15).
Check for compressor oil leak at front shaft seal in pulley and clutch assembly. Replace
compressor if there is more than a minor dry patch (para. 25-20).
Check compressor for oil leaks. If leaking at compressor hose junction, replace seals
(para. 25-30). Any other compressor housing leaks require compressor replacement
(para. 25-20).
b. If air conditioner compressor runs intermittently or is inoperative, check clutch air gap (space
between pulley and front clutch plate) with feeler gauge. Gap must-be within range of 0.016 -
0.031 in. (0.406 - 0.787 mm). If gap is out of specification, replace compressor (para. 25-20).
c. If compressor runs roughly, perform the following:
Step 1.
Discharge air conditioning system (para. 25-15).
Step 2.
Disconnect field coil harness connector from field coil.
Step 3.
Rotate compressor shaft clockwise (facing compressor) using 3/4-in. socket and wrench on
shaft nut.
Step 4.
Check for severe rough spots or catches while rotating shaft nut. If rough spots or catches
are observed, replace compressor (para. 25-20).
END OF TESTING!
14-21
