Troubleshooting Checklist for Refrigeration Systems

TROUBLE : High condensing pressure

POSSIBLE CAUSE :
-Air or non-condensable gas in system.
CORRECTIVE MEASURE :
-Purge air from condenser

POSSIBLE CAUSE :
-Inlet water warm.
CORRECTIVE MEASURE :
-Increase quantity of condensing
water.

POSSIBLE CAUSE :
-Insufficient water flowing through condenser.
CORRECTIVE MEASURE :
Increase quantity of water.

POSSIBLE CAUSE :
-Condenser tubes clogged or scaled.
CORRECTIVE MEASURE :
Clean condenser water tubes.

POSSIBLE CAUSE :
-Too much liquid in receiver, condenser tubes submerged in liquid refrigerant.
CORRECTIVE MEASURE :
Draw off liquid into service cylinder.

POSSIBLE CAUSE :
-Insufficient cooling of air-cooled condenser.
CORRECTIVE MEASURE :
Check fan operation, cleanliness of condenser, and for adequate source of air flow.

TROUBLE : Low condensing pressure.

POSSIBLE CAUSE :
Too much water flowing through condenser.
CORRECTIVE MEASURE :
Reduce quantity of water.

POSSIBLE CAUSE :
Water too cold.
CORRECTIVE MEASURE :
Reduce quantity of water.

POSSIBLE CAUSE :
Liquid refrigerant flooding back from evporator.
CORRECTIVE MEASURE :
Change expansion valve adjustment, examine fastening of thermal bulb.

POSSIBLE CAUSE :
Leaky discharge valve.
CORRECTIVE MEASURE :
Remove head, examine valve.
Replace and found defective.

TROUBLE : High auction pressure.

POSSIBLE CAUSE :
Overfeeding of expansion valve.
Leaky suction valve.
CORRECTIVE MEASURE :
Regulate expansion valve, .check
bulb attachment.
Remove head, examine valve and
replace if worn.

TROUBLE : Low suction pressure.

POSSIBLE CAUSE :
Restricted liquid line and expansion valve or suction screens.
CORRECTIVE MEASURE :
Pump down, remove, examineand clean screens.

POSSIBLE CAUSE :
Insufficient- ref-rigerant in system.
CORRECTIVE MEASURE :
Check for refrigerant storage.


POSSIBLE CAUSE :
Too much oil circulating in system.
CORRECTIVE MEASURE :
Check for too much oil in circulation.
Remove oil.

POSSIBLE CAUSE :
Improper adjustment of expansion valves
CORRECTIVE MEASURE :
Adjust valve to give more flow.

POSSIBLE CAUSE :
Expansion valve power element dead or weak.
CORRECTIVE MEASURE :
Replace expansion valve power element

POSSIBLE CAUSE :
Low refrigerant charge.
CORRECTIVE MEASURE :
Locate and repair leaks.
Charge refrigerant.

TROUBLE : Compressor short cycles on low-pressure control.

POSSIBLE CAUSE :
Thermal expansion valve not feeding properly.
1. Dirty strainers.
2. Moisture frozen in orifice or orifice plugged with dirt.
3. Power element dead or weak.

CORRECTIVE MEASURE :
Adjust, repair, or replace thermal expansion valve.
1. Clean strainers.
2. Remove moisture or dirt (Use system dehydrator).
3. Replace power element.

TROUBLE : Compressor short cycles on low-pressure control (continued)..

POSSIBLE CAUSE :
Water flow through evaporators restricted or stopped.
Evaporator coils plugged, dirty, or clogged with frost.
-Defective low-pressure control switch.

CORRECTIVE MEASURE :
Remove restriction.
Check water flow.
Clean coils or tubes.
-Repair or replace low-pressure control switch.

TROUBLE : Compressor runs continuously.

POSSIBLE CAUSE :
Shortage of refrigerant.
Leaking discharge valves.

CORRECTIVE MEASURE :
Repair leak and recharge system.
Replace discharge valves.

TROUBLE : Compressor short cycles on high-pressure control switch.

POSSIBLE CAUSE :
Insufficient water flowing through condenser, clogged condenser.
-Defective high-pressure control.

CORRECTIVE MEASURE :
Determine if water has been turned off.
Check for scaled or fouled condenser.
-Repair or replace high-pressure control switch.

TROUBLE : Compressor will not run.

POSSIBLE CAUSE :
-Seized compressor.
-Cut-in point of low-pressure control switch too high.
-High-pressure control switch does not cut-in.
1. Defective switch.
2. Electric power cut off.
3. Service or disconnect switch open.
4. Fuses blown.
5. Overload relays tripped.
6. Low voltage.
7. Electrical motor in trouble.
8. Trouble in starting switch or control circuit.
9. Compressor motor stopped by oil-pressure differential switch.

CORRECTIVE MEASURE :
-Repair or replace compressor.
-Set L.P. control switch to cut-in at correct pressure.
-Check discharge pressure and reset H.P. control switch.
1. Repair or replace switch.
2. Check power supply.
3. Close switches.
4. Test fuses and renew if necessary.
5. Reset relays and find cause of overload.
6. Check voltage (should be within 10 percent of nameplate rating).
7. Repair or replace motor.
8. Close switch manually to test power supply.
If OK check control circuit including temperature and pressure controls.
9. Check oil levels in crankcase.
Check oil pressure.

TROUBLE : Sudden loss of oil from crankcase.

POSSIBLE CAUSE :
Liquid refrigerant slugging back to compressor crankcase.

CORRECTIVE MEASURE :
Adjust or replace expansion valve.

TROUBLE : Capacity reduction system fails

POSSIBLE CAUSE :
Hand-operating stem of capacity control valve not turned to automatic position.

CORRECTIVE MEASURE :
Set hand-operating stem to automatic position.

TROUBLE : Compressor continues to operate at full or partial load.

POSSIBLE CAUSE :
Pressure-regulating valve not opening.

CORRECTIVE MEASURE :
Adjust or repair pressure-regulating valve.

TROUBLE : Capacity reduction system fails to load cylinders.

POSSIBLE CAUSE :
Broken or leaking oil tube between pump and power element.

CORRECTIVE MEASURE :
Repair leak.

TROUBLE : Compressor continues to operate unloaded.

POSSIBLE CAUSE :
Pressure regulating valve not clossing.

CORRECTIVE MEASURE :
Adjust or repair pressure regulating valve.

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