York Gas Furnace: TM9X/TM9E

Re: Flashing Code 5

Code 5 = Roll-out switch circuit has opened or low voltage fuse blown.

• The control will operate the supply air blower and inducer while the open limit condition exists.

► An LP Gas Pressure Switch may be wired in series with the roll-out limits, so low LP gas pressure may also be misinterpreted by the control board as an open roll-out.

CHECKOUT:

1. Check Low Voltage Fuse

• Check for 24VAC from each side of the low voltage fuse (on the control board) to "C".
  • Power on Both Sides = Fuse OK ⇒ Step 2. Check Rollout Circuit
  • Power on One Side Only = Blown Fuse → Install a resettable mini-breaker & check for a low voltage short.

2. Check Roll-Out Circuit

• DO NOT ATTEMPT TO RESET ANY ROLL-OUT LIMITS YET!
• At the 12-Pin plug on the control board, check for 24VAC between Red/Blk on Terminal 5 and "C".
• At the 12-Pin plug on the control board, check for 24VAC between Red/Wht on Terminal 11 and "C".
  • Power at Both Terminals + Code 5 = Bad Control Board
  • Power on One Terminal Only = Rollout Circuit Open
    • Check for 24VAC from both sides of each Rollout Limit to "C" (May also have an LP Gas Pressure Switch in series).
      • Power on Both Sides = Rollout Limit Closed
      • Power on One Side Only = Rollour Limit Open
        • Press the reset button on the open limit and recheck power. 
          • Limit Won't Reset = Bad Rollout Limit
          • Limit Resets ⇒ Step 3. Check Burners

3. Check Burners

• Observe the burners as the furnace ignites.
• Make sure all the burners light smoothly and no flame roll-out.
  • ​​​​​​​Roll-out before the blower starts = Clogged Heat Exchanger
• Observe the burners when the blower starts.
  • ​​​​​​​Roll-out or significant flame change when the burners start = Bad Heat Exchanger​​​​​​​