TM 9-2320-280-34
AIR-CONDITIONING
TROUBLESHOOTING SYMPTOM INDEX
TROUBLESHOOTING
MALFUNCTION
AIR-CONDITIONING
PROCEDURE
NO.
MALFUNCTION
PAGE
AIR-CONDITIONER
1.
Insufficient cooling . . . . . . . . . . . . . .
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2.
Intermittent cooling . . . . . . . . . . . . .
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3.
Insufficient cooling . . . . . . . . . . . . . .
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4.
Unusual noise with clutch engaged . .
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5.
Unusual noise with clutch disengaged
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6.
Incorrect oil level or leak. . . . . . . . . .
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AIR-CONDITIONER
1. INSUFFICIENT COOLING
a. Check for Refrigerant Loss
Step 1. Connect manifold gauge to low and high service connectors (para. 14-17 or 14-27.1).
Step 2.
Start vehicle engine and adjust speed to 1500 rpm (TM 9-2320-280-20).
Step 3.
Set thermostat switch and fan switch to maximum position (TM 9-2320-280-10).
Step 4.
Run vehicle with air-conditioner on for five minutes.
Step 5.
Check low side of manifold gauge for normal to low reading and high side for low reading (table 2-2
or 2-2.1). If these conditions occur, perform leak test, repair leaks, evacuate, and recharge as necessary
b. Check for Air or Moisture in System
Step 1. Perform malfunction 1a, steps 1 through 4.
Step 2.
Check low side of manifold gauge for normal to high reading (table 2-2 or 2-2.1). If sight glass has no
bubbles, tiny bubbles, or occasional bubbles, discharge system, replace dryer bottle (para. 14-19 or 14-27.3),
c. Check Expansion Valve
Step 1. Perform malfunction 1a, steps 1 through 4.
Step 2.
Check high side of manifold gauge for high reading and low side for low reading (possible vacuum)
(table 2-2 or
2-2.1). If
discharge (evaporator) air is
cool, expansion valve sweating or
frosted, or
control tube
loose, either reposition control tube or replace expansion valve (para. 14-21 or 14-27.5).
NOTE
If control tube must be repositioned, re-wrap bulb with insulating tape.
Step 3.
Check high side of manifold gauge for high reading and low side for high reading (table 2-2 or 2-2.1). If
discharge (evaporator) air is warm, replace expansion valve (para. 14-21 or 14-27.5).
d. Check Thermostatic Switch
Step 1. Perform malfunction 1a, steps 1 through 4.
Step 2.
Check low and high side manifold gauge readings for normal reading (table 2-2 or 2-2.1). If system runs
continuously, remains in on (evaporator freeze-up) or off (poor cooling) cycle, or is inoperative, but can be
made operative by jumping battery to clutch power load wire, then relocate temperature sensor, perform
electrical troubleshooting (TM 9-2320-280-20) or replace thermostat unit, as necessary (para. 14-15).
Change 2