DIRECT SUPPORT TROUBLESHOOTING PROCEDURES - continued

TM 9-4120-430-14

0042 00

FAULT PROCEDURE 4.

COMPRESSOR STARTS, BUT STOPS AT ONCE OR AFTER SHORT RUN

PERIOD. (Due to Tripped High Pressure Switch)

MALFUNCTION

TEST OR INSPECTION

CORRECTIVE ACTION

COMPRESSOR STARTS, BUT STOPS

Step 1.

Perform pressure testing on system to determine if an overcharge of refrigerant is indicated. See WP

If overcharged, partially discharge the system and retest. See WP 0044 00 and WP 0050 00.

Step 2.

Check for proper operation of condenser fan and motor.

Replace bad motor or fan. (Refer to WP 0037 00.)

Step 3.

Inspect condenser coil, intake grill and condenser discharge louvers for dirt, obstructions or closed

discharge louver.

Clean or remove obstruction or set discharge louver to full open. See WP 0060 00.

Check linear-actuator linkage for missing hardware.

Step 4.

Turn off power; short-circuit (jumper) the high pressure switch. Turn on power, wait one minute for

time delay to allow compressor to start. Allow compressor to run for a maximum of 12 seconds to

see whether compressor operates normally.

If operation of unit is satisfactory, replace faulty high pressure switch. See WP 0055 00.

FAULT PROCEDURE 5.

COMPRESSOR STARTS, BUT STOPS AT ONCE OR AFTER SHORT RUN

PERIOD. (Due to Tripping of Compressor Internal Overload)

MALFUNCTION

TEST OR INSPECTION

CORRECTIVE ACTION

COMPRESSOR STARTS, BUT STOPS

CAUTION

Do not exceed 12-second operating time for compressor as high pressure may develop in

the refrigeration system that could cause the pressure relief valve to open or may result in

damage to the system.

Step 1.

Check compressor current draw at moment of trip.

If over specified current draw, replace faulty compressor. See WP 0059 00.

Step 2.

Check for proper operation of refrigerant expansion valve superheat at compressor suction.

If in excess of 25 degrees F (-3.88 degrees C) replace expansion valve. See WP 0057 00.

0042 00-4