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Fault Code Troubleshooting Guide
connector. Refer to chart #2 (p.33) for expected resistance value. If the measured resistance is >200Ω
or =0Ω, the thermisitor is faulty.
• Replace thermisitor assembly.
Control board faulty-
• Replace control board.
• If replacing the control board doesn’t resolve the issue, contact technical support.
Coil Temperature Sensor Short or Open or Ad Error (Coil temperature sensor circuit is
not functioning):
Loose connection or damaged wire-
• Turn off power at the circuit breaker / fuse box.
• Check that connector CN212 on control board is seated.
• Check wires for damage.
Discharge temperature sensor is shorted or open-
• Unplug ribbon cable from CN212; check resistance between pins 5 and 6 of the ribbon cable
connector, refer to chart #1 (p.33) for expected resistance value. If the measured resistance is >40Ω
or = 0Ω, the thermisitor is faulty.
• Replace thermisitor assembly.
Control board faulty-
• Replace control board.
• If replacing the control board doesn’t resolve the issue, contact technical support.
Low Water Level Alarm (The tank is not full of water):
Tank is not completely fi lled with water-
• Ensure that the tank is completely fi lled and cycle power off and back on to restart dry fi re protection.
Fault is still present-
• Call tech services.
Heat Pump Low Pressure Fault (Lower pressure switch is open):
Low suction pressure-
• Use a service gage set to check system pressures (high and low sides).
• The low side pressure switch opens if suction pressure drops below 7.3 psi. and will reset (close)
when pressure exceeds 21.8 psi; if suction pressure is less 21.8 psi, the low pressure switch is open,
preventing the compressor from running.
• Can be caused by poor air fl ow across the evaporator; make sure the evaporator and air fi lter are free
of dust and dirt build up, see “Cleaning the Air Filter” (p.11) and “Cleaning the Evaporator” (p.35).
• Can be caused by low refrigerant charge or a blockage in the refrigerant system.
Low side pressure checks good-
• Disconnect the wires from the low pressure switch and check.
Heat Pump High Pressure Fault (High pressure switch is open):
High discharge pressure-
• Use a service gage set to check system pressures (high and low sides).
• The high pressure switch opens at 338 psi and resets when pressure drops below 275 psi.; if it is 275
psi or higher then the pressure switch is open, preventing the compressor from running.
• Can be caused by poor air fl ow across the evaporator; make sure the evaporator and air fi lter are free
of dust and dirt build up, see “Cleaning the Air Filter” (p.11) and “Cleaning the Evaporator” (p.35).
• Can be caused by blockage in the refrigerant system or low water level in tank.
High side pressure is less than 275 psi.-
• Disconnect the wires from the high pressure switch and check resistance across the terminals; 0