# Problem with Goodman Furnace/AC System



## james404 (Apr 29, 2012)

Ok, have a Goodman GMNT080-4b Furnace/Air handler.   We bought the house  last summer, and AC was fine for the rest of the summer, Heat worked  just fine all winter.  When we went to turn it back to ac, the outside  unit starts as normal, inside unit started up, we get good cool air, for  about 3-5 minutes, then the indoor blower cuts off.  Turns back on a  few seconds later.  This repeats with shortening time of the blower  running, till I cut it off.

The diagnostic light on the control board is on constantly, showing normal operation.  It never blinks any codes.

Started  out checking for anything burnt, loose, etc.   And haven't found  anything amiss.  Went ahead and replaced the capacitor, with no  change.   Tested the motor with an ohm-meter, and all the values seem to  add up:
Common to Run -- 2.3,   Start to Common -- 3.4, Start to Run 5.5, so was assuming motor was ok.


So  was thinking it had to be in control board, so rigged up an external  switch to test the blower.  Turned on switch, blower ran for 5 minutes  straight, about till I thought I'd figured it out, then cut off.   Flipped switch off, and immediately back on and blower started up again   immediately.  The only thing I can think of to cause it to switch off  now, would be a thermal shutdown within the motor itself.  Ran it again  till it quit on its own, noticed there was a slight squeal or whistle  just before the motor shut off.  Immediately opened the panels to check  the temp of the motor, and only 30 seconds after it shuts down the motor  is only slightly warm to the touch, not near scalding like I would  expect (I have a large fan that would burn you in comparison when it has  been on for a while).   

So any ideas on what I should look for  next?   If it really is the blower motor how can I make sure besides  replacing it?  If not what else is the likely cause?

Appreciate any help you can give.


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## lloyd (May 20, 2012)

I'd replace the run capacitor on the blower motor for grins. They are only a few dollars from a supply house.


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## mail2hap (Jul 21, 2012)

James404: Did you figure out the problem with your Goodman fan motor? I have one doing the exact same thing! Puzzling.
Thanks
Hap


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## runfast (Sep 16, 2012)

noise indicates bearing trouble


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