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: |
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Open Roll-Out |
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Bad Roll-Out Limit |
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Bad Primary Limit |
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Bad Blower Motor |
2 |
Bad Control Board |
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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