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SERVICE DIAGNOSIS CHART

Symptom Cause Remedy

Compressor 1. Motor Line open. 1. Close starter or disconnect switch
does not run 2. Fuse blown 2. Replace fuse
3. Tripped overload 3. See electrical section
4. Control contacts dirty or jammed in 4. Repair or replace
open position
5. Piston seized 5. Remove motor-compressor head, look for
broken valve and jammed parts.
6. Frozen compressor or motor bearings 6. Repair or replace.
Unit short 1. Control differential set too close 1. Widen differential
cycles 2. Discharge valve leaking 2. Replace valve plate
3. Motor compressor ??? 3. Check for high head pressure, tight bearings,
seized pistons, clogged air-cooled condenser.
4. Refrigerant shortage 4. Repair leak and recharge.
5. Refrigerant over charge 5. Remove some refrigerant.
6. Cycling on high pres. cutout 6. Check condenser / or non condensable in system
Compressor 1. Improperly wired 1. Check wiring against diagram
will not start - 2. Low voltage 2. Check main line voltage - determine location
Hums of voltage drop
intermittently 3. Relay contacts not closing 3. Check my operating manually. Replace relay
if defective
4. Open circuit in start-winding 4. Check stator leads. If leads are all right,
replace stator.
5. Stator winding grounded 5. Check stator. If leads are all right, replace stator.
6. High discharge pressure 6. Eliminate cause of excessive pressure
7. Tight compressor 7. Check oil level. Correct binding.
Unit operates 1. Control contacts sticking in closed position. 1. Clean points or replace control.
long or 2. Insufficient refrigerant in system 2. Check for leaks. Repair and add charge
continuously 3. Dirty condenser. 3. Clean condenser
4. Air or non-condensables in system 4. Purge high point in system
5. Compressor inefficient 5. Check valves and pistons
6. Improper wiring 6. Check wiring and correct if necessary
Fixture 1. Insufficient refrigerant in system 1. Check for leaks. Repair and add charge
temperature 2. Control set too high 2. Reset control
too high 3. Control wiring loose 3. Check wiring to control
4. Expansion valve or strainer plugged 4. Clean or replace
5. Compressor inefficient 5. Check valves and pistons
6. Expansion valve set too high 6. Lower setting
7. Iced or dirty coil 7. Defrost or clean coil
8. Unit too small 8. Add unit or replace
9. Clogged or small refrigerant lines 9. Clear line or increase line size
10. Oil logged in system 10. Remove excessive oil, check refrigerant charge
High 1. Refrigerant overcharge 1. Remove the excess
discharge 2. Non-condensables in system 2. Remove the non-condensables
pressure 3. Dirty condenser coil 3. Clean
4. High side restriction 4. Check all valves or remove restriction
5. Head pressure control setting 5. Adjust controls
6. Fan not running 6. Check electrical circuit