Geothermal Heat Pump: Climatemaster

Re: Diagnostic Codes

CXM Board - Most older Climatemaster Geothermal heat pumps use the CXM Control Board.

• The CXM board has a diagnostic function that will cause the unit to go into a "lockout" if an abnormal operating condition occurs.
• When the CXM board enters a "lockout" mode, the LED on the control board will flash continuous to indicate that a fault code exists.
• A "lockout" can be Reset by turning the thermostat system switch to "Off" and back "On".
  • Turning power to the unit "Off" will Reset the lockout, but will also erase the fault memory.
• To retrieve the last "lockout" code, momentarily short the "TEST" pins on the control board.

FAULT DESCRIPTION:

• No Faults in Memory = 1 Flash
  • No faults. Normal operation.
• High Pressure Lockout = Code 2
  • When the high pressure switch opens due to high refrigerant pressures the compressor relay is de-energized immediately since the high pressure switch is in series with the compressor contactor coil.
  • The high pressure fault recognition is immediate (does not delay for 30 continuous seconds before de-energizing the compressor).
• Low Pressure Lockout = Code 3
  • The low pressure switch must be open and remain open for 30 continuous seconds during “on” cycle to be recognized as a low pressure fault. If the low pressure switch is open for 30 seconds prior to compressor power up it will be considered a low pressure (loss of charge) fault.
  • The low pressure switch input is bypassed for the initial 60 seconds of a compressor run cycle.
• Water Coil Low Temperature (FP1) = Code 4
  • The FP1 thermistor temperature must be below the selected low temperature limit setting for 30 continuous seconds during a compressor run cycle to be recognized as a FP1 fault.
  • JW3 Clipped = 10 deg. Unclipped = 30 deg.
  • The FP1 input is bypassed for the initial 120 seconds of a compressor run cycle.
  • FP1 is set at the factory for one try. Therefore, the control will go into lockout mode once the FP1 fault has occurred.
• Air Coil Low Temperature (FP2) = Code 5
  •  The FP2 thermistor temperature must be below the selected low temperature limit setting (30 deg. unclipped) for 30 continuous seconds during a compressor run cycle to be recognized as a FP2 fault.
  • The FP2 input is bypassed for the initial 120 seconds of a compressor run cycle.
  • FP2 is set at the factory for one try. Therefore, the control will go into lockout mode once the FP2 fault has occurred.
• Condensate Overflow = Code 6
  • The condensate overflow sensor must sense overflow level for 30 continuous seconds to be recognized as a CO fault. Condensate overflow will be monitored at all times.
• Over/Under Voltage Shutdown = Code 7
  •  An over/under voltage condition exists when the control voltage is outside the range of 18VAC to 31.5VAC.
  • Over/under voltage shut down is a self-resetting safety. If the voltage comes back within range for at least 0.5 seconds, normal operation is restored.
  • This is not considered a fault or lockout. If the CXM is in over/under voltage shutdown for 15 minutes, the alarm relay will close.
• Unit Performance Sentinel warning = Code 8
  •  The UPS feature indicates when the heat pump is operating inefficiently.
  • A UPS condition exists when: a) In heating mode with compressor energized, FP2 is greater than 125°F [52°C] for 30 continuous seconds, or: b) In cooling mode with compressor energized, FP1 is greater than 125°F [52°C] for 30 continuous seconds, or: c) In cooling mode with compressor energized, FP2 is less than 40°F [4.5°C] for 30 continuous seconds.
  • If a UPS condition occurs, the control will immediately go to UPS warning.
  • The status LED will remain on as if the control is in normal mode.
  • Outputs of the control, excluding LED and alarm relay, will NOT be affected by UPS.
  • The UPS condition cannot occur during a compressor off cycle.
  • During UPS warning, the alarm relay will cycle on and off. The cycle rate will be “on” for 5 seconds, “off” for 25 seconds, “on” for 5 seconds, “off” for 25 seconds, etc.
• Swapped FP1/FP2 Sensors = Code 9
  • During test mode, the control monitors to see if the FP1 and FP2 thermistors are in the appropriate places.
  • If the control is in test mode, the control will lockout, with code 9, after 30 seconds if: a) The compressor is on in the cooling mode and the FP1 sensor is colder than the FP2 sensor, or: b) The compressor is on in the heating mode and the FP2 sensor is colder than the FP1 sensor

WHAT TO CHECK: