Low heat from Goodman furnace

Old 01-05-09, 07:38 PM
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Post Low heat from Goodman furnace

Hello all,

I have a Goodman (White Rodgers) 36f22, I believe. I do not seem to be getting good heat output, mainly when the temps get pretty low. It is now 40deg. Earlier the heat was on and blew very warm air and was 55 outside. My max temp in the house is about 74 but the furnace seems to stay on all night being that it cannot reach the desired temp.

I've tried to reset the system and all is the same. I have no LED signal from the intergrated control module, my filter is relatively clean, my fuse is good.

I have never touched the furnace before being that I bought this house new and lived here for almost 4 yrs now. I've never had a problem before this.

Any thoughts anyone--thanks.
Old 01-05-09, 10:03 PM
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I'd start by taking the cover off the burner compartment of the furnace and getting acquainted with the sequence of events that your furnace goes through to produce heat.

I'd turn the thermostat 'way up, watch that process until it stabilizes at some point, then turn the thermostat down until it shuts off. Repeat three or four times until you are familiar with this procedure and can describe it here.

From your description, it sounds like the furnace may be shutting off on the limit switch. Using an AC voltmeter to find out if that switch is opening would be worthwhile.
Old 01-06-09, 08:58 AM
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And how big is your house in square feet, how new or old is this house, what do you know about it's insulation-doors-windows and what is the input and output rating on the furnace's nameplate, which will be printed inside the furnace, inside the big panel, on the side.

And if I understand your post right, when it is already 74 in the house, it keeps putting out low heat and keeps running all night? What does a thermometer stuck down a register closest to the furnace actually read?

And are cold outside temps expected yearly, where you live? (Edit) Ohhh....Houston. Nope. But 40-55 is. Anyway, please answer my questions.

Also adding that I'm sure you have A/C built ontop the furnace, and I would like to know if you know if the blower puts out lots of forceful air out the registers or if it seems paltry or even if it seems like TOO much air blowing out, incase someone has your blower speed on too high a speed for the btu rating, for example.

And have you ever found your furnace filter plugged up? Or have you ever ran the furnace without a filter in it? Because if you have, that could mean blockage of the A-coil of the A/C above the furnace.

Last edited by ecman51; 01-06-09 at 09:09 AM. Reason: added lot's more

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