TM 9-2320-280-34
Section III. AIR-CONDITIONING TROUBLESHOOTING
2-8. GENERAL
Information in this section is used by support maintenance personnel to diagnose and correct air-
conditioning system malfunctions.
2-9. AIR-CONDITIONING TROUBLESHOOTING INSTRUCTIONS
Before taking any action to correct a possible air-conditioning malfunction, perform the following:
(1) Question vehicle operator about nature of complaint and conditions under which problem occurs.
(2) Record symptoms and compare symptoms of listed malfunctions to help identify problem.
(3) Conduct visual inspection of system to identify obvious problems (loose belts or fittings,
disconnected wires, dirty condensor, or evaporator surfaces, blown fuses, and massive leak).
2-10. INITIAL TEST CONDITIONS
b. Ensure a full charge of refrigerant is in system at start of test.
(1) Check sight glass reading for low refrigerant indication.
NOTE
Gauge readings taken at normal engine idle may not accurately
reflect condition of system.
c. Set engine speed at 1500 rpm (TM 9-2320-280-20).
d. Set air-conditioner cooling and blower speed settings to maximum value (TM 9-2320-280-10).
e. Open vehicle doors to permit fresh flow of air through passenger/ambulance compartment.
f. Allow vehicle to run with air-conditioner on for at lease five minutes to allow temperature and
pressure stabilization.
2-11. SYSTEM PERFORMANCE EVALUATION
a. Measure temperature of outlet duct in ambulance compartment by inserting end of thermometer to
center air duct louver. Normal operation duct temperature is between 40-50F (4-10C), while ambient
temperature is 70F (231C) and humidity is low.
NOTE
In a properly functioning system, duct temperature will increase as
the ambient air temperature and humidity increases.
b. Low and high side gauge readings on manifold gauge set are used to identify and diagnose system
problems. Refer to table 2-2 or 2-2.1 for normal low and high side pressure readings.
c. After troubleshooting repair, evacuation and recharging are complete, conduct performance test of
system.
d. Perform pressure gauge and in-vehicle cold air duct readings to confirm system has been restored to
peak operating condition.
e. Verify refrigerant level is correct before returning vehicle to service.
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