System information
25
Table 9 - Troubleshooting chart
Symptom Cause Remedy
Compressor and outdoor fan Power Failure - Call power company
will not start Fuse blown or circuit breaker tripped - Replace fuse or reset circuit breaker
Defective thermostat, contactor, transformer, control relay,
defrost board, or high-pressure or loss-of-charge/low pressure switch - Replace component
Insufficient line voltage - Determine cause and correct
Incorrect or faulty wiring - Check wiring diagram and rewire correctly
Thermostat setting too high - Lower thermostat setting below room temperature
Units have a 5-minute time delay - DO NOT bypass this compressor time delay - wait for 5 minutes
until time-delay relay is de-energised
Phase monitor - Correct incorrect power supply
Compressor will not start but condenser Faulty wiring or loose connections in compressor circuit - Check wiring and repair or replace
fan runs Compressor motor burned out, seized, or internal overload open - Determine cause.
- Replace compressor
Defective overload - Determine cause and replace
One leg of 3-phase power dead - Replace fuse or reset circuit breaker. Determine cause
Low input voltage (20 percent low) - Determine cause and correct
Power leads running out of phase - Change 2 leads of 3-phase power supply
Compressor producing a low pressure Scroll compressor is rotating in the wrong direction - Correct the direction of rotation by reversing the 3-phase power
differential (not pumping properly) leads to the unit
Compressor cycles (other than normally Refrigerant overcharge or undercharge - Recover refrigerant, evacuate system, and recharge to capacities
satisfying thermostat) shown on nameplate
Defective compressor - Replace and determine cause
Insufficient line voltage - Determine cause and correct.
Blocked outdoor coil - Determine cause and correct
Defective overload - Determine cause and correct
Defective thermostat - Replace thermostat
Faulty outdoor fan motor - Replace
Damaged reversing valve - Determine cause and correct
Restriction in refrigerant system - Locate restriction and remove
Compressor operates continuously Dirty air filter - Relace filter
Unit undersized for load - Decrease load or increase unit size
Thermostat set too low - Reset thermostat
Low refrigerant charge - Locate leak, repair, and recharge
Frosted coil with incorrect defrost operation - Check defrost time settings
- Reset as necessary
- Check defrost temperature switch
- Replace as necessary
Air in system - Recover refrigerant, evacuate system, and recharge
Outdoor coil dirty or restricted - Clean coil or remove restriction
Excessive head pressure Dirty air filter - Replace filter
Dirty indoor or outdoor coil - Clean coil
Refrigerant overcharged - Recover excess refrigerant
Air in system - Recover refrigerant, evacuate system, and recharge
Heating: Indoor air restricted or recirculating - Determine cause and correct
Cooling: Outdoor air restricted or recirculating - Determine cause and correct
Head pressure too low Low refrigerant charge - Check for leaks, repair and recharge
Restriction in liquid tube - Remove restriction
Excessive suction pressure Heating: Outdoor coil frosted - Move timer on control board to 30 minutes between defrost cycles
Cooling: High heat load - Check for source and eliminate
Reversing valve hung up or leaking internally - Replace valve
Refrigerant overcharged - Recover excess refrigerant
Suction pressure too low Cooling: Dirty air filter - Replace filter
Heating: Outdoor coil frosted - Move timer on control board to 30 minutes between defrost cycles
Low refrigerant charge - Check for leaks, repair and recharge
Metering device or low side restricted - Remove source of restriction
Cooling: Insufficient coil air flow - Increase air quantity
- Check filter - replace if necessary
Cooling: Temperature too low in conditioned area - Reset thermostat
Cooling: Outdoor ambient temperature below 13°C - Install low-ambient kit
Filter drier restricted - Replace
Compressor runs but outdoor fan NC (normally closed) contacts on defrost board open - Check condition of relay on board
does not - Replace if necessary
Indoor fan motor does not run Fan wheel not secured to shaft - Properly tighten fan wheel to shaft
Insufficient voltage at motor - Determine cause and correct
Power connectors not properly seated - Connectors should snap easily; do not force
Indoor fan motor operation is Water dripping into motor - Verify proper drip loops in connector wires
intermittent Connectors not firmly seated - Gently pull wires individually to be sure they are crimped into the
housing