Hi, I have Heil Ultimate II gas furnace with about 13 yrs old. The furnace is working OK except the fan would never stop as long as the furnace is on, therefore, it will blow the cold air when the heating stops. I also tried to disconnect the wire from the board, and fan will still not stop. What can be the problem? Thanks

Defective fan relay on the board would be suspect if you removed the G/Green wire from the circuit board and the fan keeps running when the rest of the furnace operation is normal.

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Originally Posted by hvac1000

Defective fan relay on the board would be suspect if you removed the G/Green wire from the circuit board and the fan keeps running when the rest of the furnace operation is normal.

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So do I need to replace the board? Is there any switch relay on this model? As I also have an air conditioner, but it's broken now, and I wonder if there is anyting to do from the air conditioner?

Thank you so much for your help.

I will ask again. Did you remover the G green wire from the circuit board? Did the fan keep running after you removed the wire or did it stop running?

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Originally Posted by hvac1000

I will ask again. Did you remover the G green wire from the circuit board? Did the fan keep running after you removed the wire or did it stop running?

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Yes, I removed the green wire, and once I turn on the furnace, the fan still run. My model is NTC5100BFD1, and serial# L963052640.

The technician told me he can't find any fan switch, everything seems go through the circuit board, but he is not sure if it's from the circuit board and another technician told me that the fan motor needs to be replaced. I am so confused.

Thank you so much

If the blower is working then the fan motor in the blower should not be bad. If there is no fan and limit control then the circuit board controls the fan operation and the circuit board is probably defective.

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Originally Posted by hvac1000

If the blower is working then the fan motor in the blower should not be bad. If there is no fan and limit control then the circuit board controls the fan operation and the circuit board is probably defective.

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Thank you for your help.

Have a nice day

No Problem.

I have the same probleme with my ultimate 3 , I don't know if it's a probleme or built like that but my fan is always ON winter and summer 24h a day , the only way to stop it is to switch the breaker in the power panel to OFF , Did you find if it was normal??