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Fan keeps running

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Gmein
Gmein Member Posts: 4
in THE MAIN WALL
I had to replace a control unit on a dual pack roof mounted unit that has not been running on the heat side for three years now. I install the valve, set the t-stat and called for heat. It fired off and all is well for putting out some heat. I can shut the t-stat down and the burner will go off, although the blower will continue to run. I had to pull the fuse in order to get the blower fan to shut off. I will plug the disconnect blade when I go back out in the morning and see what is up. Any suggestions as to what it may be. I am working on a Wheatherking GPG with a Honeywell VR8204M control. Thanks to all

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  • nicholas bonham-carter
    nicholas bonham-carter Member Posts: 8,578
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    fan problems

    what happens when you disconnect the thermostat wiring to this unit?

    it's probably a wiring/thermostat problem, or the limit switch.--nbc
  • Techman
    Techman Member Posts: 2,144
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    Fan runs

    How long did you wait for the fan to shut off ,after the t'stat was satisfied?
  • Gmein
    Gmein Member Posts: 4
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    Fan keeps running

    I will disconnect the t-stat in the morning and see what we get. Thanks
  • Gmein
    Gmein Member Posts: 4
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    Fan keeps running

    aFTER i SHUT THE T-STAT TO TURN THE BURNER OFF THE FAN RAN FOR 20 MINUTES. i TURNED THE T-STAT BACK UP TO 80 DEGREES AND IT CALLED FOR HEAT AGAIN AND IT FIRED OFF. i LET IT RUN FOR 15 MINUTES AND SHUT IT DOWN AND THE FAN CONTINUED TO RUN. i DID THIS AGAIN BY SETTING THE T-STAT AND IT FIRES OFF EACH TIME. tHE FAN JUST KEEPS RUNNING. i HAD TO REMOVE THE DISCONNECT  BLADETO SHUT THE FAN OFF. iN THE MORNING i WAS GOING TO GO BACK OUT AND PUT THE DISCONNECT BLADE BACK IN TO SEE IF THE FAN WAS GOING TO COME ON.
  • Tim McElwain
    Tim McElwain Member Posts: 4,628
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    Sounds like you have

    a printed circuit board problem (Integrated Fan Control) or there is some limit seen open by the board which will cause this to happen. Make sure filters are clean, look for auxiliary fan switch (Located usually behind the fan blower housing) and make sure it is not opening prematurely.



    Three things will cause what is happening:



    1. Some limit is open as fan will always run if a limit opens to protect heat exchanger from thermal stress.



    2. Dip switches for fan off not set correctly on the board.



    3. A defective board usually one of the relays on the board sticking.
  • Gmein
    Gmein Member Posts: 4
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    Fan keeps running

    I put the disconnect blade back in and fire it off, it brought heat and upon turning off five times, the fan would go off when the thermostat switch was moved to off. This was all tried early in the morning. In the evening I turned on again and after running for 15 min I turned the unit off and the circulation fan continues to run. I had to shut off at the panel again. I have it on again this morning and after shutting off the unit the fan will turn off after 2 minutes. Works every time. I will have to try it in the evening again and see how it acts. After the fuel is shut off, is it a signal that the fire is off and the fan continues to push the air through the ducts until the burner is cooled off. What part is responsible for this, is it the control module on the inside of the heat side or could it be the heating sensor at the burner, any help will do.
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