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1. Symptom: Compressor will not start
Possible Causes
High pressure switch open
Compressor overload opened
No power to module
Phase monitor open or tripped
Breaker tripped
Overcurrent
Ambient temperature is lower than 0°F
2. Symptom: Compressor will not run
Possible Causes
Ambient temperature is lower than -5°F
Main switch open or circuit breakers open
Fuse is blown
Investigate for possible overloading
Defective contactor or coil
3. Symptom: Compressor has excessive noise or vibration
Possible Causes
Flooding of refrigerant back to compressor
Improper phase sequence
Improper or worn compressor support (vibration-isolating mounting)
Faulty crankcase heater
4. Symptom: Compressor Loading/Unloading Cycles Too Short
Possible Causes
Temperature differential set too low
Incorrect liquid temperature settings
Insufficient evaporator water flow
Low system liquid/water volume
5. Symptom: Compressor loses oil
Possible Causes
Low refrigerant charge
Oil trapped in the system
Defective crankcase heater
ARTC-SVX009A-EN
Heat Pump Troubleshooting
Potential Solutions
High pressure event has occurred; check fan settings and functionality; check
obstructed coils; check pressure switch functionality.
Allow motor to cool and reset; High amp load/floodback; compressor
operating outside of operating envelope.
Check breakers and fuses; energize from module electrical and control panel.
Check phase sequence, unbalanced voltage, overvoltage, undervoltage; loss
of phase.
Reset breaker; check amp draw, high refrigeration pressure, low voltage, and
lose connection.
Check overload (circuit breaker, compressor grounded).
Ambient temperature should be above 0°F.
Potential Solutions
Ambient temperature should be above -5°F.
Check circuits and motor winding for shorts or grounds.
Replace fuse or reset breakers.
Overloads are auto-reset. Monitor to assure the overload does not re-occur.
Determine type and cause. Correct fault before resetting safety.
Potential Solutions
Check setting of expansion valve; check crankcase heater.
Check phase sequence.
Replace support.
Replace crankcase heater.
Potential Solutions
Ramp/set temperature differential setpoint, check stage up/down settings.
Select proper control settings.
Check flow rate.
Water system volume needs to be increased.
Potential Solutions
Check for leaks and repair. Add refrigerant to proper charge.
Low refrigerant velocity caused by operation outside operating envelope;
check fan settings and functionality in heating mode.
Replace crankcase heater.
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