Operating instructions

TM 11574A-OI
3-49
IV. TROUBLESHOOTING AND FAULT ISOLATION PROCEDURES
Troubles or operating malfunctions which may occur on the Large Field Refrigerated System and
associated components. After remedial action has been taken, testing of affected equipment
shall be carried out to insure that it is serviceable and in satisfactory operating condition.
3-8 Troubleshooting
a. Compressor does not run.
Step Probable Cause Remedy
1 Main power line open. Replace fuse or reset circuit breaker.
If fault is not corrected proceed to step 2.
2 Safety thermostat tripped. Reset thermostat.
If fault is not corrected proceed to step 3.
3 Control stuck open. Replace control.
If fault is not corrected proceed to step 4.
4 Loose terminal connection. Check connections.
If fault is not corrected proceed to step 5.
5 Improperly wired controls. Check wiring and rewire.
If fault is not corrected proceed to step 6.
6 Low line voltage. Check line voltage. Determine location of
voltage drop.
If fault is not corrected proceed to step 7.
7 Compressor motor defective. Check motor winding for open or short.
Replace compressor if necessary.
If fault is not corrected proceed to step 8.
8 Seized compressor Replace compressor.
b. Compressor cycles on low pressure control.
Step Probable Cause Remedy
1 Low pressure control erratic in action. Raise differential setting, check capillary for
pinches, replace control.
If fault is not corrected proceed to step 2.
2 Suction shutoff valve partially closed. Open valve.
If fault is not corrected proceed to step 3.