TM9-4120-400-14
TROUBLESHOOTING - continued
Table 5-1.
MALFUNCTION
TEST OR INSPECTION
C O R R E C T I V E ACTION
2.
COMPRESSOR SHORT CYCLES. - continued
Step 2. Check head pressure (low pressure side). (See para 5-19.)
Add refrigerant if low. (See para 5-16.)
Step 3. Check quench valve. (See para 5-23.)
Replace if defective.
Step 4. Check compressor motor internal overload switch. (See para 5-35.)
Replace compressor if motor internal overload switch is defective.
Step 5. Check solenoid valves L1 and L2. (See para 5-24 and 5-25.)
Replace or replace if defective.
INSUFFICIENT COOLING.
NOTE
Frost on the evaporator coil is usually caused by an obstruction to air flow or dirty coils,
filter, or mist eliminator.
Step 1. Check actuating cylinder to make sure condenser discharge louvers are opening. (See para 5-27.)
Replace if defective.
Step 2. Check sight glass after operating unit for 15 minutes with TEMPERATURE SELECTOR switch in
maximum COOLER position. Center should be bubble free and green.
If charge is low add refrigerant. (See para 5-16.) Bubbles may also be caused by clogged
dehydrator. (See para 5-20.)
Step 3. Check for refrigerant leaks. (See para 5-14.)
Repair or change defective part.
Step 4. Check solenoid valves L1 and L2. (See para 5-24 and 5-25.)
Repair or replace if defective.
Step 5. Check pressure regulator valve. (See para 5-26.)
Replace if defective.
Step 6. Check expansion valve for proper operation. (See para 5-22.)
Replace if defective.
5-4
