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    iaoear's Avatar
    iaoear Posts: 7, Reputation: 1
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    #1

    Nov 21, 2009, 02:29 PM
    Furnace lights but blows cold air
    Hello, I'm hoping someone can help me figure out what's wrong with my furnace. I believe it is a Goodman GMP/GMPE gas furnace but I'm not sure snce I can't find that information anywhere on the appliance. About a week ago it started blowing out only cold air. I though it might be a thermostat issue so I replaced the old thermostat with a new electronic one but that has not solved the problem. The pilot light goes on and it goes through it's cycle of (supposedly) heating up. The last few days it's sometimes blown hot air, sometimes warm air and sometimes cold air. What could be the problem? Thank you.
    KC13's Avatar
    KC13 Posts: 2,556, Reputation: 99
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    #2

    Nov 21, 2009, 02:59 PM
    Metal, or PVC flue/exhaust? Look for a status LED behind a clear viewer in the front panel.
    iaoear's Avatar
    iaoear Posts: 7, Reputation: 1
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    #3

    Nov 21, 2009, 03:09 PM
    There is a red light near the bottom behind the clear viewer. I believe it's a metal exhaust. There is a large metal tube coming out of the top.
    KC13's Avatar
    KC13 Posts: 2,556, Reputation: 99
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    #4

    Nov 21, 2009, 03:18 PM
    If the LED is steady, set thermostat to demand heat & observe LED. Blinking indicates a problem. Observe/note pattern.
    iaoear's Avatar
    iaoear Posts: 7, Reputation: 1
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    #5

    Nov 21, 2009, 03:19 PM

    I tried that and the light stays steady.
    KC13's Avatar
    KC13 Posts: 2,556, Reputation: 99
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    #6

    Nov 21, 2009, 03:21 PM
    Try this: turn off power & disconnect wire from "R" terminal at thermostat. Turn power back on. What happens?
    iaoear's Avatar
    iaoear Posts: 7, Reputation: 1
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    #7

    Nov 21, 2009, 03:25 PM

    There is no 'R' terminal. Only 'RC' and 'RH' and they're attatched by a jumper wire.
    KC13's Avatar
    KC13 Posts: 2,556, Reputation: 99
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    #8

    Nov 21, 2009, 03:35 PM
    The jumper is good, but there should be another wire connected to either "RC" or "RH". Usually red.
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    iaoear Posts: 7, Reputation: 1
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    #9

    Nov 21, 2009, 03:37 PM

    Okay, so disconnect the wire coming from the wall ('RC') from the thermostat and then turn it back on, right?
    KC13's Avatar
    KC13 Posts: 2,556, Reputation: 99
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    #10

    Nov 21, 2009, 03:41 PM
    Yes. Leave thermostat off base for now, and make sure "R" wire (only 24 volts) isn't touching anything.
    iaoear's Avatar
    iaoear Posts: 7, Reputation: 1
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    #11

    Nov 21, 2009, 03:47 PM

    I will try that and let you know if it works in a little while. Thank you for all of your help, I hope this fixes it!
    KC13's Avatar
    KC13 Posts: 2,556, Reputation: 99
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    #12

    Nov 21, 2009, 03:51 PM
    No, this isn't a FIX, this is a STEP. Toward, hopefully, a FIX.
    iaoear's Avatar
    iaoear Posts: 7, Reputation: 1
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    #13

    Nov 23, 2009, 05:21 PM
    Thanks for all of the help KC13 but, unfortunately, it looks like I'm going to have to buy a new furnace altogether.

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