TROUBLE SHOOTING CHART
SYMPTOM
CAUSES
CHECK & CORRECTIVE MEASURE
Units runs OK, but short
cycles on.
1. Check the cause.
2. Differential set too close - widen.
3. (a) Check airflow to the condenser
correct.
(b) Reduce refrigerant charge.
(c) Purge.
4. (a) Fix leak, add refrigerant.
(b) Replace device.
Unit operates long or
continuously.
Head pressure too high.
Head pressure too low.
1. Shortage of refrigerant.
2. Control contacts stuck or frozen
closed.
3. Refrigerated or air conditioned space
has excessive load or poor insulation.
4. System inadequate to handle load.
5. Evaporator coil iced.
6. Restriction in refrigeration system.
7. Dirty condenser.
8. Filter dirty.
1. Refrigerant overcharge.
2. Air in system.
3. Dirty condenser.
4. Malfunction of condenser fan (air-
cooled).
5. Excessive air temperature entering
condenser.
6. Restriction in discharge line.
1.Low ambient temperatures (air-
cooled).
2. Refrigerant shortage.
3. Damaged valves in compressor.
1. Fix leak, add charge.
2. Clean contacts or replace control.
3. Determine the fault and correct.
4. Replace with larger system.
5. Defrost.
6. Determine location and remove.
7. Clean condenser.
8. Clean or replace.
1. Correct the refrigerant charge.
2. Recharge the system after a thorough
triple evacuation.
3. Clean.
4. Check and correct or replace.
5. Check for short circuiting of con-
denser discharge air, correct it.
6. Correct it.
1. Install fan cycling switch, if not pro-
vided. Check the setting and opera-
tion, if provided.
2. Correct the refrigerant charge after
leak testing.
3. Repair/replace the compressor.
1. Overload protector.
2. Thermostat.
3. High pressure cut-out due to:
(a) Insufficient air.
(b) Overcharge.
(c) Air in system.
4. Low pressure cut-out due to:
(a) Undercharge.
(b) Restriction in expansion device.
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1. High load on evaporator. Load in ex-
cess of design conditions.
2. Unbalanced system. Oversized air
handling unit matched with under
sized condensing unit.
3. Compressor discharge valve leaking.
4. Expansion valve widely open.
5. Improper bulb location or installation.
1. Check the design.
2. Follow manufacturer's guide line and
correct it.
3. Repair/replace compressor.
4. Check and adjust the superheat ac-
cordingly.
5. Check the expansion valve bulb is
properly tighten at correct location.
High suction pressure.