Classic HVPA & HVPSA M&S 8.09-1
15700 - 20
HVAC Equipment
Electrical (cont’d)
Problem/Symptom
Likely Cause(s)
Correction
No voltage on line side
of compressor contactor.
Blown fuses or tripped circuit breaker.
Improper wiring.
1.
2.
Check for short in wiring or unit.
Recheck wiring diagram.
1.
2.
Improper voltage.
High voltage.
Low voltage.
Single phasing (3 phase).
1.
2.
3.
Power supply problem.
Power supply problem.
Wiring undersized.
Loose connections.
Check incoming power and fusing.
1.
2.
3.
Contamination
Moisture.
Poor evacuation on installation or
during service.
1.
In each case, the cure is the same,
recover refrigerant. Add filter drier,
evacuate and recharge.
1.
High head pressure.
Non-condensibles air.
1.
Unusual head and
suction readings.
Wrong refrigerant.
1.
Foreign matter -
copper fittings.
Copper tubing cuttings.
1.
Copper oxide.
Dirty copper piping.
1.
Welding scale.
Nitrogen not used.
1.
Soldering flux.
Adding flux before seating copper
part way.
1.
Excess soft solder.
Wrong solder material.
1.
Loss of Lubrication
Low suction pressure.
Low charge.
Refrigerant leaks.
1.
2.
Check system charge.
Repair and recharge.
1.
2.
Cold, noisy compressor
- slugging.
Dilution of oil with refrigerant.
1.
Observe piping guidelines.
1.
Noisy compressor.
Migration.
1.
Check crankcase heater.
1.
Cold, sweating
compressor.
Flooding.
1.
Check system charge.
1.
Low load.
Reduced air flow.
Thermostat setting.
1.
2.
Dirty filter.
Dirty coil.
Wrong duct size.
Restricted duct.
Advise customer.
1.
2.
Short cycling of
compressor.
Faulty pressure control.
Loose wiring.
Thermostat.
1.
2.
3.
Replace control.
Check all control wires.
In supply air stream, out of
calibration.
Customer misuse.
1.
2.
3.
Flooding
Poor system control
using a TXV.
Loose sensing bulb.
Bulb in wrong position.
Wrong size TXV.
Improper superheater setting.
1.
2.
3.
4.
Secure the bulb and insulate.
Relocate bulb.
Use correct replacement.
Adjust, if possible, replace if not.
1.
2.
3.
4.
