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  1. #1

    Goodman GMT090-4A gremlin

    This is a ten year old unit that I just inherited as part of a home purchase. Problem simply stated. The unit operates normally in the heat mode as long as the fan switch is in the "on" position. Fan speed performs as it should. All is well in this configuration. But wait! If you try to heat with the fan switch in the "auto" position, the unit will only go through a single heat cycle (operates normally). After this single cycle, the "all is well " led will go out after a varying amount of time and the unit is dead until you either remove the power from the unit or put the thermostat in the "off" position. After some period of time (up to an hour or so) repowering will bring the led back on or, if just using the thermostat off function, the led comes back on by itself. An initial assumption was that a hot situation was the culprit but on three occassions simply moving the therm switch to heat without the fan in the "on" position was enough to cause the led to go out. The thermostat is the second one installed with no difference in symptoms. My thanks to any help offered.

  2. #2
    Join Date
    Mar 2013
    Location
    Springville, NY
    Posts
    2,686
    change your filter and if that doesnt fix it, call in a professional for further diagnosis.
    ~~
    Nest is poo...

  3. #3
    Join Date
    May 2008
    Location
    Missouri
    Posts
    3,424
    We are forbidden is assist with DIY repairs by site rules. Sorry!

  4. #4

    Goodman GMT090-4a gremlin

    Quote Originally Posted by HVAC_Marc View Post
    change your filter and if that doesnt fix it, call in a professional for further diagnosis.
    Filter change accomplished early on. Thanks. Was not looking for a diy fix. Was hoping for a informed idea as to the problem to avoid being ripped off. Sadly, not all HVAC folks are reputable. Sorry.

  5. #5
    Join Date
    May 2008
    Location
    Missouri
    Posts
    3,424
    Don't use a pleated air filter as the excessive restriction could cause unit to "lock off" due to limit tripping! If you've got a pleated filter, remove it and see what happens. If works fine, then get a non-pleated to replace it.

  6. #6
    Join Date
    Mar 2013
    Location
    Springville, NY
    Posts
    2,686
    Quote Originally Posted by rczapf View Post
    Sadly, not all HVAC folks are reputable. Sorry.
    This is true of any kind of job - hvac, plumber, dentist, lawyer, etc.

    It sounds like your system may have a wiring problem of some sort. I've seen it in other units where the high limit will cut out, not reset, and break the entire 24 volt circuit. I've also seen hacks rewire the low voltage circuit to carry high voltage, with the same result - the switch opens, doesnt reset, and everything is broken.
    ~~
    Nest is poo...

  7. #7

    Goodman GMT090-4a gremlin

    Quote Originally Posted by HVAC_Marc View Post
    This is true of any kind of job - hvac, plumber, dentist, lawyer, etc.

    It sounds like your system may have a wiring problem of some sort. I've seen it in other units where the high limit will cut out, not reset, and break the entire 24 volt circuit. I've also seen hacks rewire the low voltage circuit to carry high voltage, with the same result - the switch opens, doesnt reset, and everything is broken.
    Agreed. Especially lawyers.

    Backing up slightly, I ran the unit for a short trial with no filters at all. Current filters are non-pleated.

    Marc. Your reply gives me ammunition for confronting the alleged "pro" that will show up. Even searching through Angies list doesn't guarantee results, much less satisfactory ones. Regardless, I have no interest in diy'ing this thing. I am in my late 60's and just want to be able to hold my own. I am confident that my tech will be decent rather than a rip off artist. I like to find out early rather than late. Thank you for your concern and help. How close are you to Pensacola?

  8. #8
    Join Date
    Mar 2013
    Location
    Springville, NY
    Posts
    2,686
    1500 miles
    ~~
    Nest is poo...

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