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Waterfurnace - Fault Codes

Article ID: 283
Last updated: 19 Apr, 2017

Geothermal Heat Pump: Waterfurnace

Re: Diagnostic Codes

These units can have either an Aurora Base Control (ABC) or an Aurora Expansion Board (AXB).

  • The ABC board has a diagnostic function that will cause the unit to go into a "lockout" if an abnormal operating condition occurs.
  • When the ABC 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.

DIAGNOSTIC CODES:
Flashing Description
1 No faults in memory
2 High pressure fault
3 Low pressure fault
4 Water coil freeze-protect (heating)
5 Air coil freeze protect (cooling)
7 Condensate overflow fault
8 Over/Under voltage fault (<18 or >31.5 VAC)
11 FP1 & FP2 Swapped

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 7
    • 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 8
    •  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.
  • Swapped FP1/FP2 Sensors = Code 11
    • 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

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Article ID: 283
Last updated: 19 Apr, 2017
Revision: 3
Views: 4913
Comments: 0