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TM9T - Flashing Code 5

Article ID: 614
Last updated: 24 Dec, 2022

York Gas Furnace: TM9T

Re: Flashing Code 5

Code 5 = Roll-out switch has opened its normally closed contacts or low voltage fuse blown.

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

 The primary limit is wired in series with the roll-out limits, so an extended opening of the primary limit may also be interpreted by the control board as an open roll-out.


Qty Possible Causes:
Open Roll-Out
Bad Roll-Out Limit
Bad Primary Limit
Bad Blower Motor
2 Bad Control Board
Clogged/Blocked Heat Exchanger


CHECKOUT:

1. Check Roll-Out Limits

  • Initiate a call for heat by energizing W1.
  • DO NOT ATTEMPT TO RESET ANY ROLL-OUT LIMITS YET!
  • Check for 24VAC between both sides of each roll-out limit and "C".
    • Power on Both Sides = Limit Closed
    • No Power at Either Limit → Step 2. Check Primary Limit
    • Power on One Side Only = Limit Open
      • Attempt to reset any open limit(s) by pushing its reset button, then recheck for 24VAC.

2. Check Primary Limit

  • Check for 24VAC between both sides of the primary limit and "C".
    • Power on Both Sides = Limit Closed → Step 3. Check Burners
    • Power on One Side Only = Limit Open

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.

4. Check Control Board/Blower Motor

  • Check the blower motor operation in both Low and Hi fire (W1 & W2).
    • Low Fire
    • Blower Operates Normally ⇒ Check Hi Fire (W2).
    • Blower never starts or only starts when burners shut off on Code 4.
      • Reset furnace and Check for 120VAC between "Lo Heat" and Neutral after burner fire.
        • ​​​​​​​No Power = Bad Control Board
        • Power + No Blower Operation = Bad Blower Motor/Capacitor
    • Hi Fire
    • Blower Shuts Off on Hi Fire (W2).
      • Check for 120VAC between "Hi Heat" and Neutral.
        • ​​​​​​​No Power = Bad Control Board
        • Power + No Blower Operation = Bad Blower Motor/Capacitor

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Article ID: 614
Last updated: 24 Dec, 2022
Revision: 7
Views: 33
Comments: 0