OPERATIONAL CHECKOUT AND TROUBLESHOOTING PROCEDURES

TM 9-4120-428-14

0012 00

DIRECT SUPPORT MAINTENANCE

AIR CONDITIONER, HORIZONTAL, COMPACT

(NSN 4120-01-502-1319)

OPERATIONAL CHECKOUT AND TROUBLESHOOTING PROCEDURES

NOTE

Before proceeding with the troubleshooting procedures, check Troubleshooting

Procedures for Unit Maintenance.

TROUBLESHOOTING PROCEDURE

COMPRESSOR WILL NOT START.

SYMPTOM

The compressor will not start.

MALFUNCTION

The LOW and HIGH-pressure switches are tripped.

CORRECTIVE ACTION

Check that both the LOW and HIGH PRESSURE switches are not tripped. To

reset, press and release the LOW and HIGH PRESSURE switches. If the switch

does NOT stay in, check and/or replace the switches. (WP 0084 00) and (WP

The compressor motor thermal cutoff switch is not operational.

CORRECTIVE ACTION

Conduct an operational check on the compressor motor thermal cutoff switch. If

the thermal cutoff switch is defective, replace the compressor. (WP 0090 00).

The compressor shows signs of burnout.

CORRECTIVE ACTION

Replace the compressor if it shows signs of burn out. (WP 0090 00).

TROUBLESHOOTING PROCEDURE

COMPRESSOR SHORT CYCLES

SYMPTOM

The compressor short cycles.

MALFUNCTION

The head pressure is either too high or too low.

CORRECTIVE ACTION

1. Check the head pressure (high pressure side). (WP 0000 00).

a) If the pressure is too high, check the HIGH PRESSURE cutout switch and

replace if defective. (WP 0083 00).

b) If the pressure is excessive and the sight glass is clear, release any excess

refrigerant. Release the pressure until the requirements of (WP 0074 00) are met.

2. Check the head pressure (low pressure side) and add refrigerant if low.

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