DNZ - Fault Codes / Diagnostic Codes

York Package Units: DNZ

Re: Fault Codes

While in lockout, the control board keeps the pilot gas valve, main gas valve and induced draft motor de-energized.

Lockouts due to failed ignition or flame losses may be reset by removing the call for heat (W1) for more than 1 second, but less than 20 seconds, or by removing power from the control for over 0.25 seconds. The control will automatically reset lockout after 60 minutes.

Lockouts due to detected internal control faults will reset after 60 minutes or power interruption.

CODE 2 = Pressure Switch Stuck Open - The inducer motor is energized but the pressure switch is in the open position.

• Bad Switch
• Bad Inducer Motor

CODE 3 = Pressure Switch Stuck Closed - The inducer motor is de-energized and the pressure switch is in the closed position.

• Bad Switch
• Stuck Relay on ICB

CODE 5 = 5 Consecutive Loss of Flame - The flame sensor detects the presence of pilot flame. Flame is not detected 5 in consecutive ignition attempts.

• Dirty Flame Sensor
• Dirty Pilot Orifice
• Low Pilot Pressure
• Bad Gas Valve
• Bad ICB

CODE 6 = High Limit Open - Any time the high temperature limit switch is open the control board will run the indoor blower motor on heat speed, the inducer (on high speed for 2 stage models), de-energize the gas valve, and flash "6" on the LED. When the high temperature switch closes, the control will restart the ignition sequence beginning with pre-purge.

• Low Airflow
• Bad Limit
• High Gas Pressure

CODE 7 = Rollout Switch Open - If the rollout switch opens for more than 0.25 seconds, the control board will run the inducer (on high speed for 2 stage models) for a post-purge period, immediately de-energize the gas valve, and flash "7" on the LED.

The blower output will be energized during an open rollout condition. If the rollout switch closes, the control shall remain locked out until power removed or "W" is removed.

Rollout switch lockout shall not reset automatically.

CODE 8 = Flame Present with Gas Off - If flame is sensed for longer than 4.0 seconds during a period when the gas valve should be closed, the control will enter lockout flashing "8" on the LED. The control will turn on the inducer blower while the flame is present.

CODE 9 = Gas Valve Stuck Off or On - If either or both Pilot and Main Gas valve outputs are sensed to be off for more than 1 second when commanded to be on, the control board shuts off all outputs and enters a hard lockout flashing "9" on the LED.

The only way to recover from a hard lockout is to remove and then reapply 24VAC power to the control board.

CODE 10 = Flame Sense Circuit Failure - If the control detects an internal hardware failure in the flame sense circuit, it shuts off all outputs and enters a hard lockout flashing "10" on the LED. The control will not respond to thermostat demands during a hard lockout.

The only way to recover from a hard lockout is to remove and then reapply 24VAC power to the control. If problem persist after removal and reapplication of 24VAC power, the board may need to be replaced.