Classic HVPA & HVPSA M&S 8.09-1
15700 - 19
HVAC Equipment
Compressor Overheating (cont’d)
Problem/Symptom
Likely Cause(s)
Correction
High head pressure.
Overcharge.
Dirty heat pump coil.
Faulty or wrong size heat pump
fan motor.
Faulty outdoor blower.
Recirculation of air.
Additional heat source.
Non-condensibles
1.
2.
3.
4.
5.
6.
7.
Check system charge.
Clean coil.
Replace fan motor.
Replace blower.
Replace with correct rotation motor.
Correct installation.
Check for recirculating from other equip-
ment.
Recover refrigerant, evacuate and
recharge system.
1.
2.
3.
4.
5.
6.
7.
Short cycling of
compressor.
Faulty pressure control.
Loose wiring.
Thermostat.
TXV.
Capillary Tube.
Low charge.
Low evaporator air flow.
Faulty run capacitor.
Faulty internal overload.
1.
2.
3.
4.
5.
6.
7.
8.
9.
Replace pressure control.
Check unit wiring.
Located in supply air stream.
Differential setting too close.
Customer mis-use.
Internal foreign matter.
Power element failure.
Valve too small.
Distributor tube/tubes restricted.
Restricted with foreign matter.
Kinked.
I.D. reduced from previous compressor
failure.
Check system charge.
Dirty coil.
Dirty filter.
Duct too small or restricted.
Replace.
Replace compressor.
1.
2.
3.
4.
5.
6.
7.
8.
9.
Faulty compressor
valves.
Fast equalization/low pressure
difference.
1.
Replace compressor and examine system
to locate reason.
1.
Electrical
Voltage present on load
side of compressor con-
tactor and compressor
won’t run.
Run capacitor.
Internal overload.
Compressor windings.
1.
2.
3.
Check with ohmmeter.
Allow time to reset.
Check for current ohms.
1.
2.
3.
Voltage present on line
side of compressor
contactor only.
Thermostat.
Compressor control circuit.
1.
2.
Check for control voltage to
compressor-contactor coil.
High pressure switch.
Low pressure switch.
Compressor turned off/on control or
interlock.
1.
2.
