Goodman GMH95 gas furnace "open high limit"


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Old 10-06-13, 07:31 PM
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Goodman GMH95 gas furnace "open high limit"

I have a Goodman GMH95 natural gas furnace. The blower motor or fan seems to be making a ton of noise. I investigated and during the process a wire dropped out (fell out of terminal) It appears to be the white wire from the Central Air Unit that runs into the blower motor. I put it where I thought it fell out of, but I turned on the heater (1st time this year) and it ran for 2 minutes and the gas shut off and now I'm getting 4 red flashes which is and error for "open high limit" which makes me believe I put the wire in the wrong spot. Nothing is blocked and filter is new. Any one know where the white wire from the Central Air Unit should go? I know the board is labeled, but the green wire was attached to the blue label and the blue terminal was loose so I assumed that is where the white wire dropped out.

Thanks,
 
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Old 10-06-13, 08:04 PM
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The white wire from your blower motor should go to a terminal on the board where all of the white wires are connected in an area that says Neutral. All you need to do is find the terminal in that area that is open and plug the white wire there. I believe it is the terminal closest to the end of the board. The green wire is probably a ground wire. The blue wire should go to one terminal on the primary limit control. Your primary limit control opened because your blower wasn't operating causing the furnace to overheat and shutdown.
 

Last edited by firedawgsatx; 10-06-13 at 08:28 PM.
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Old 10-06-13, 08:34 PM
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The link for the service manual:
Goodman mfg -GMH95.pdf

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The neutrals are inside the red box.
 
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Old 10-06-13, 08:46 PM
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Thanks for the reply. The group of wires in question runs from the outside ac unit to the blower motor board. It has two wires (white and red). Ther is a slice in the wire before it goes into the furnace board. The white stays white, but I'm not sure where it goes. The red changes to green and is plugged into the blue "C" terminal. The splice from the board has a blue and red but they are not used.
The fan was running the entire time but the burners kicked off and I got a open high limit warning and just the fan kept running.
 
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Old 10-06-13, 08:49 PM
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The white wire should go to the "Y" terminal on the control board. If you look at the photo PJMax posted it is color-coded as yellow on the left-hand side.
 
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Old 10-06-13, 08:50 PM
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The white wire looks to plug into the y w r g c terminals, not the neutral area.
 
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Old 10-06-13, 08:52 PM
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It appears to be the white wire from the Central Air Unit that runs into the blower motor.
Your original post stated it ran into the blower motor, hence the confusion. From outside the condenser has two wires that run back to the inside unit; one to the common terminal "C" and one to the "Y". In your case green wire goes to "C" and the white wire to "Y".

The fan was running the entire time but the burners kicked off and I got a open high limit warning and just the fan kept running.
The high limit will normally open when there is an over-temp condition such as restricted air flow or the blower is not running.
 
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Old 10-06-13, 09:01 PM
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Yes, sorry. It runs to the board on unit (on the blower housing). It looked like the Y was the loose terminal, but I plugged it in and I got the same problem. The furnace kicks on and so does the burners for a few minutes, then the burners turn off and I get tehe 4 red flashes meaning "open high limit". The filter is new and nothing is plugging the system from what I can see. The main reason for looking into this is the blower motor or blower fan was making a lot of noise at the end of the AC season. Now I need the furnace and I still have the vibration. It seems like the fan is out of balance and causing my noise. Could a vibrating fan cause and "open high limit" error?
 
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Old 10-06-13, 09:59 PM
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Not enough air flow will cause an open high limit error.
It sounds like your blower motor has issues and is not moving enough air.
 
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Old 10-07-13, 05:58 AM
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I don't know what to do next. I thought before I read your post that it was the blower fan. My fan seems like it is vibrating excessive. I found a video on YouTube ("diy blower wheel replacement" YouTube v=6dzq3sz3w6s) and if you watch from 5:56-6:24 my fan does the same thing and moves around like the welds are broke. But would this cause low air flow and open high limit alarm or should I buy both the fan and the motor?
Thanks
 
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Old 10-07-13, 07:00 AM
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my fan does the same thing and moves around like the welds are broke. But would this cause low air flow and open high limit alarm or should I buy both the fan and the motor?
Only you can make that decision. Since none of us are physically there to evaluate what is happening with your blower we can't make a determination. There is obviously something going on to cause the vibration. I suggest you remove the blower motor from the housing and inspect the wheel to see if the welds are broken and observe how it spins and to see if the bearings are good.
If the blower wheel is not spinning properly it can definitely make a difference in air flow output.
 
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Old 10-08-13, 11:56 AM
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Your gmh is a newer furnace which should be covered by a 10 year parts warranty - if the blower wheel or motor needs to be changed, call a goodman dealer. (there's a dealer locator on their website)
 
 

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