Trouble Shooting - Daikin UCQ0060 Installation Operation & Maintenance

9.0 TROUBLE SHOOTING

PROBLEM
LACK OF COOLING EFECT
TRIPPING OF
COMPRESSOR(S)
EXCESSIVE BELT
"SCREAM" WHEN FAN(S)
START UP
POSSIBLE CAUSE
1. Faulty compressor or lack of
compression.
2. Temperature of air entering
evaporator too high.
3. Fouled condenser and/or
evaporator tube surface.
4. Low refrigerant charge.
5. Thermal expansion valve out of
adjustment or erratic.
6. Improper air flow through
evaporator.
7. Room thermostat not operating
properly.
A. DUE TO LOW PRESSURE CUT OUT
1. Reduced air flow through
evaporator.
2 Low refrigerant charge.
3. Broken expansion valve.
4. Restricted refrigerant line.
5. Faulty low pressure cut-out.
B. DUE TO HIGH PRESSURE CUT-OUT
1. Air in refrigeration system.
2. Excess refrigerant charge.
3. Faulty high-pressure cut-out.
C. DUE TO COMPRESSOR OVERLOAD TRIPPING
1. Compressor over-current, under
voltage or single phasing.
2. Excessive discharge pressure.
3. Compressor over-heating due to
low refrigerant.
4. Compressor motor has a
winding shorted.
5. Liquid refrigerant in
compressor causing valve plate
damage and lack of compression.
6. Defective overload protector.
1. Slipping belts.
ACTION
1. Check discharge pressure for
compression. Inspect compressor
and replace if necessary.
2. Reduce load to design KW
value.
3. Inspect surface and clean.
4. Repair refrigerant leak, add
refrigerant.
5. Adjust superheat or replace
power element.
6. Determine flow and adjust
correctly belt tension.
7. Inspect thermostat and replace
if necessary.
1. Inspect surface & clean, check
evaporator fan drive
2. Repair refrigerant leak, add
refrigerant.
3. Replace expansion valve.
4. Determine the cause of
restriction and repair.
5. Replace.
1. Re-evacuate refrigeration
system and charge with new
refrigerant.
2. Bleed off excess refrigerant.
5. Replace.
1. Check electrical supply,
contactors, wiring, and rectify
fault.
2. See section B above.
3. Check refrigerant charge (fix
leak), top up refrigerant if
necessary.
4. Replace compressor.
5. Check that crankcase heater is
functioning properly.
6. Replace protector.
1a. Apply belt dressing/belt
tensioning.
1b. Adjust belt tension correctly.
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