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Model RT Energy Recovery Unit
Troubleshooting – Refrigeration Circuit
Symptom
Possible Cause
Corrective Action
Compressor starts
but cuts out on high
pressure switch
High pressure
activates at
600 psig for R410a
Refrigerant overcharge.
Check pressures, charge by subcooling.
In cooling mode low water flow rate.
Increase water flow rate.
In heating mode low air flow over air coil.
Change filter or clean air coil.
Air or non-condensables in system.
Check high side equalized pressure reading with
equivalent outdoor temperature.
Defective high pressure switch.
Replace.
Restriction in discharge or liquid line.
Check refrigerant line pressures, check thermal
expansion valves.
Reheat valve and bypass valve not opening.
Check valves or valve circuit board.
Compressor cuts out
on thermal overload
Low voltage.
Check voltage.
Sustained high discharge pressure.
Check running amperage and conditions
described under ‘Low suction pressure’
symptoms.
High suction and discharge pressures.
Check thermal expansion valve setting, check for
air in system.
Defective compressor overload.
If compressor is hot, allow compressor to cool
for two hours. Recheck for open circuit.
Improper refrigerant charge.
Check subcooling.
Improperly wired.
Review wiring schematics.
Loose wiring.
Check all connections and wires.
Defective start relay.
Replace relay.
Motor windings damaged.
Verify amp draw.
Compressor hums,
but will not start
Improperly wired.
Review wiring schematics.
Low line voltage.
Check voltage.
Loose wiring.
Check all connections.
Defective start or run capacitor.
Check run capacitor for compressor and fan
motor.
Defective relay start.
Replace relay.
Motor winding damaged.
Verify amp draws.
Internal compressor mechanical damage.
Replace.
Always have a completed Pre Start-Up Checklist, unit Start-Up Checklist, and Optional Accessories Checklist prior to requesting parts or
service information.
