42
ohms indicates good; high resistance indicates the switch is defective and should be replaced.
Heat Pump High Temperature Fault (Compressor discharge temperature is too high):
The refrigerant system may be blocked-
• Check the heat pump piping and evaporator; if the tubing or evaporator is covered with frost in
one spot, this indicates there is a restriction in the system at that point. Call technical services for
assistance.
Check the condition of the compressor-
• See the “Compressor Check Flowchart” (p.28).
Water temperature is too high-
• The control board is not controling the tank temperature properly
• Check the upper and lower tank thermisitors; make sure they are in contact with the tank wall.
• Check the tank temperature sensors, see “Temperature Sensors” (p.32).
Main Control Board Crystal Fault (Main board failure):
Faulty control board-
• Replace the control board.
• If replacing the control board doesn’t resolve the issue, contact technical support.
Main Control Board RAM Fault (Main board failure):
Faulty control board-
• Replace the control board.
• If replacing the control board doesn’t resolve the issue, contact technical support.
Main Control Board ROM Fault (Main board failure):
Faulty control board-
• Replace the control board.
• If replacing the control board doesn’t resolve the issue, contact technical support.
Main Control Board EEPROM Fault (Main board failure):
Faulty control board-
• Replace the control board.
• If replacing the control board doesn’t resolve the issue, contact technical support.
Main Control Board State Fault (Main board failure):
Faulty control board-
• Replace the control board.
• If replacing the control board doesn’t resolve the issue, contact technical support.
Low Supply Voltage Fault (Low input voltage):
Power supply voltage is too low-
• Verify the unit is connected to 240 VAC. Heat pump operating voltage range is 204-264 VAC. The
compressor will not operate below 204 VAC, but the heating elements will.
• If connected to 208 VAC, a buck-boost tramsformer is required to boost to 240 VAC.
High Supply Voltage Fault (High input voltage):
Power supply voltage is too high-
• Verify the unit is connected to 240 VAC, unit is intended for 240 VAC connection only. If connected
to higher voltage, a buck boost transformer may be required to reduce voltage. Heat pump operating
voltage range is 204-264 VAC. The compressor will not operate above 264 VAC, but the heating
elements will.
• If connected to 208 VAC, a buck-boost transformer is required to boost to 240 VAC.
Fault Code Troubleshooting Guide
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