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MattJ 10-02-2008 06:42 PM

Furnace won't light (Goodman GMP100-3)
I went out of town for a couple of days and turned down my heat to 60. When I got back and went to turn it back up to 70 I heard the furnace kick on, but after a couple minutes there was no warm air. I went and checked it out and I didn't see the HSI getting hot like it normally does. I unplugged the HSI and threw the volt meter on it and waited for a reading after turning it off and then back on. It read 115V after I heard the gas switch click and so it was obviously a bad HSI. I pulled it out and sure enough, it had burned out. I went to the hardware store and got the exact same one that i had burned out (larger coil style) and installed it. Unfortunately, when I turned the furnace back on the HSI was in contact with metal and grounded itself out, ruining my new purchase :censored:($35). So I went back and they gave me a universal one because they didn't have anymore of the style that I got in the first place. I put the new one in and it didn't get hot at all. So I threw the volt meter back on and now I don't get a reading at all. I checked and the small fuse (3A) was not blown. I've got a pregnant wife that's 8 months along and she is getting pretty sick of 60 degrees. Any ideas?

hvaclover 10-02-2008 07:15 PM

Try reseting the pwer to system. May be in lock out or you fried the transformer (Can happen with out blowing fuse).

Best I can do with the info you supplied.

MattJ 10-02-2008 08:54 PM

I did try resetting it by following the instructions on the front of the unit. Can the transformer be replaced without replacing the circuit board?

hvaclover 10-02-2008 10:17 PM

I think you have taken it as far as you can with out endangering more components. Time for a pro. That HSI short to ground was one of the worst things that could possibly happen.:(


MattJ 10-02-2008 11:18 PM

I checked the transformer and it reads 24V as it should. Any other ideas besides calling a pro?

hvaclover 10-02-2008 11:26 PM


Originally Posted by MattJ (Post 167820)
I checked the transformer and it reads 24V as it should. Any other ideas besides calling a pro?

I'd love to say "yes" but the truth of it is you could ruin other components if you don't know the nuances of the equipment. Cut your loses and get a guy who can comprehensively go over the machine with out making any mis-steps.

You already made one big error don't make it worse. Just giving you my professional point of view.

SD515 10-03-2008 04:05 AM

Does it now flash a code ?? (1 or 2 I think for that model...which would be a pressure switch problem) If the pressure switch fails, it won't go to ignition sequence.

If the press sw is working and you still have 24V, but not 120V going to the igniter, the board is possibly fried.

MattJ 10-03-2008 08:55 AM

It does not have a flash code, the only thing that is abnormal is no 120 to the igniter. I really don't have the $ to pay to have somebody tell me the board is fried and then pay them again to come out to replace it. What does a circuit bord cost anyways?

hvaclover 10-03-2008 09:11 AM

Well Matt if I can't presuade you to call a pro than take a chance on the board.

Dont' know what they cost in your area. Could be couple hundred.

Your wife is pregnant don't be pennywise and pound foolish.

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