Problems with Goodman GMP 075-3 not lighting


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Old 10-10-11, 08:22 AM
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Problems with Goodman GMP 075-3 not lighting

Ok, when I turn the furnace on, the fan spins and after about 10 seconds I get 3 blinking lights. I checked the pressure switch and it's working propery. I took a small drill bit and put it in the nipple on the fan housing and cleaned it out, when I put the bit in It went down about 2 inces or so and seems to have hit metal, is this correct?

If I jump the wires from the pressure switch the ignitor gets white hot but the furnace never lights. Please, I'm trying to save some money here but feel I'm out of my league with this.
 
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Old 10-10-11, 11:03 AM
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It sounds like you have cleaned out the fitting on the inducer housing which has a tendency to get plugged.

The inducer motor is presumably switching on and coming up to speed, but the pressure switch isn't closing.

The probability is that the vent or something in the furnace is plugged up and preventing a free flow of air through the furnace. Identifying what that is can be difficult, and probably requires disassembling the vent to inspect that for obstructions and then inspecting the furnace heat exchanger and related parts to check for problems there.

You may need a good repairman to help you with that. If so, you did what you could by checking for what problems you could.
 
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Old 10-10-11, 11:26 AM
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Would that cause the burners not to light when the pressure switch wires are jumpered though?
 
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Old 10-10-11, 11:46 AM
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When you turn on the thermostat, the inducer motor should turn on, come up to speed and the pressure switch should close. You shouldn't have to jumper the pressure switch.

I'd deal with that issue first.
 
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Old 10-11-11, 09:44 AM
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I also have a variable speed two-stage Goodman furnace that I installed myself several years ago. The three blinking lights may give you a clue if you have the troubleshooting guide handy. I think mine came with the furnace.

If you don't have the decode page, you might try typing "goodman furnace diagostic led" in your Google search and see what comes up.
 
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Old 10-11-11, 09:53 AM
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Got to thinking about the diagnostic code sheet and I think it may be inside the cover panel of the controller area. Three blinks may mean fault #3.
 
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Old 10-12-11, 02:26 PM
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Thanks for the replies. Turns out the switch was bad, which then burned out the board. Ended up getting a pro in. He said this was one of the most difficult furnaces he's dealt with, which makes me feel much better about not being able to figure it out.
 
 

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