York Air Handler: AHX / MX
Re: Flashing Code 6
A Fault Code 6 results from the following sequence of conditions:
- If the limit switch opens for a long duration (Fault Code 4), the control will energize the blower until power is removed from the control (heat outputs will continue to cycle as the limit resets).
- If the limit switch opens for a second long duration period during a single call for heat (Fault Code 5), the control will enter a "soft lockout" which will keep the blower locked on and lockout the heat outputs for one hour.
- If the limit switch opens multiple times soon after the soft lockout reset (Fault Code 6), the control will enter a "hard lockout" condition.
- During a "hard lockout", the control will keep all heat outputs de-energized until power is removed from the control.
- The control will de-energize the blower five minutes after entering the hard lockout condition.
To Reset: Line or Low Voltage Power to the air handler control board must be cycled.
| Qty |
Possible Causes: |
| 1 |
Clogged Air Filter |
|
Heater Stuck On |
| 2 |
Failing X-13 Motor |
|
Bad Limit(s) |
CHECKOUT:
1. Check for Water on Control Board
- Especially in counter-flow applications, the control board is extremely susceptible to water damage from condensate overflow.
- If there is water in the base of the air handler, or if the control board has obvious signs of water damage ⇒ suspect a Bad Control Board
2. Check Limits & Board
- Turn off power to the air handler.
- It is best to turn off power at the breaker box, as this test may bring you into contact with the inlet power wiring.
- Disconnect the white molex plug from the air handler control board.
- On the plug (not the board) check resistance between the Red and Brown wires.
- No Resistance Red to Brown = Open Limit
- Resistance Red to Brown = Limit Closed ⇒ Re-attach molex plug and re-power air handler.
- Limit Closed + Code 3 or 4 = Bad Control Board
3. Check Blower Operation
- Activate a call for Fan by one of the following methods:
- At the thermostat, turn the "Fan" switch to "On".
- At the air handler control board, place a jumper wire between "R" and "G".
- X-13 Motor (AHX/MX)
- Check high voltage plug for 230VAC
- Check for 24VAC between "C" and "Red" at motor.
- 230VAC + 24VAC on Red + No Blower = Bad Motor
- 230VAC + No 24VAC = Bad Control Board
4. Check Heaters
- Ensure that there is no call for heat (disconnect W1 & W2).
- Check each heater amperage.
- A heater drawing amps = Stuck Heater Relay or Bad Control Board ⇒ Confirm by checking DC voltage to the heat relays.
- No Call for Heat + DC Voltage Present = Bad Control Board
- No DC Voltage + Heater Energized = Stuck Heat Relay
5. Check Filter/Airflow
- Check air filter
- Check indoor coil
- Check duct static pressure