Refrigeration System Operating Problems

TM 10-4110-262-13&P

0028 00

8. Air in the System - Air is not condensable. Its presence in the system increases head pressure.

When the compressor is stopped, air will gather at the high point of the high side. Evacuate the

system.

9. Temperature of the Liquid Line - During normal operation, the liquid line will be slightly warmer than

the surrounding air. An extremely hot line indicates either a shortage of refrigerant or a plugged

condenser coil. A cold line indicates a restriction, and some flashing may take place in the liquid line

sight glass.

10. Restricted or Wet Dehydrator - If the outlet line of the dehydrator is colder than the inlet line, the

dehydrator is either saturated with moisture or is dirty and must be replaced.

11. Dirt in the Expansion Valve Screen Perform a low side pump down. Remove the screen and

clean. If the moisture is in the refrigeration system, it will collect at the expansion valve and freeze.

This is indicated by abnormally low suction pressure. Clean the system, replace the dehydrator,

pressurize and check for leaks, and evacuate the low side. Return the unit to normal operation.

12. Ice on the Evaporator Coil - Run the unit through a manual defrost cycle to remove the ice.

13. Air Flow - Do not load product directly in front of the evaporator air return or discharge. Ensure that

the condenser air inlet and discharge areas are clear of obstruction. Ensure that the fans (evaporator

and condenser) are correctly positioned in their respective openings and operating to achieve

maximum airflow.

14. Compressor Life - The following conditions will shorten the life of a compressor:

Operating a contaminated system

Clogged expansion valve screen

Defective high pressure or low pressure switches

Insufficient oil charge

Wrong oil or mixed oil

Insufficient refrigerant charge

Refrigeration System Operating Problems

Operating problems may result from a faulty refrigeration system component or a problem in the control

system. Use the following table to diagnose and repair problems in the refrigeration system.

Troubleshooting procedures for the ADR-300 control system are presented in the next section.

Condition

Possible Cause

Remedy

Compressor does not run

Improperly wired

Check wiring against diagram.

Low line voltage

Check line voltage-determine location of

voltage drop

Defective control circuit

Check and replace relay if defective. If not,

check control circuit

Open circuit in motor winding

Check motor and continuity between

windings and check for grounded windings.

If open, replace motor

0028 00-2