Daikin UCQ0060, Installation Operation & Maintenance

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