Goodman Blower Motor Always On

skalapeno · 03-04-2009, 12:24 PM

My issue started last night, my wife noticed only cold air was coming out of the registers. I turned the furnace off at the thermostat (set to Auto, and Off, 50 degrees), but the blower wouldn't stop running. To turn it off, I used the switch in the utility closet.

We had the blower replaced a couple months back (something with the bearings) and before the tech left, he said the hot surface igniter was getting old. I replaced the igniter this morning, but after finishing up and turning the unit on in the closet, the blower motor came on right away (thermostat still Off) and no ignition.

I think there's normally a clicking or something before ignition, there was nothing like that.

One last point, I noticed something blinking through the "peep hole" located on the bottom access panel when first looking at the unit, I haven't noticed anything blinking since (though I can't confirm either way without checking again).

My model # is GMP100-5 Rev8

Any help is much appreciated, thanks!

kenmac · 03-04-2009, 01:18 PM

blower relay on the board may be stuck. Turn on the heat & let it run through a cycle & see if it turns off after the cycle

**beenthere** · 03-04-2009, 01:21 PM

Probably tripped on high limit.
When did you change your air filter last.

skalapeno · 03-04-2009, 03:31 PM

Thanks for your replies.

I have left the unit running, but it doesn't seem to do anything but run the blower...how long should a cycle last?

We installed a 3-month at the beginning of January, another before that in October. In October--if this means anything--we had a crew come clean all the ducts and they did work cleaning the furnace as well.

skalapeno · 03-04-2009, 04:36 PM

An update...

I went home and checked for the limit and found what appears to be 3 of the limit switches (disc-like with wires coming in one side, out the other) in sequence on my unit. A wire comes from below (assuming the control board) through a switch on the left side, top, right side of the combustion area and then on to the gas control switch.

I tried the little reset button that's located between the wires on each switch, but no luck. I also replaced my 3 month filter with a blue fiberglass one.

No luck, with or without the thermostat set, when turning it on in the closet, the blower turns on right away and nothing else happens.

**beenthere** · 03-04-2009, 04:53 PM

Those are roll out switches.

The limit is larger, and I think on the right side of your unit.

Give it a tap.

skalapeno · 03-04-2009, 04:56 PM

In the upper section, correct?

I saw a circular object in the upper left of the top section, could that be it? Also, do I need to tap it while it's running, or should I have everything off first?

Thanks again

**beenthere** · 03-04-2009, 05:09 PM

Shut the furnace off, and then tap it.

Plumber101 · 03-04-2009, 06:31 PM

Goodmans are known for there crappy boards. I had a couple last year where the evap coil condensation pan melted and allowed the condensation to drain onto the board. Been doing it for a while replace pan and board.

Just my $.02

skalapeno · 03-04-2009, 08:16 PM

Wow, it worked!

Thanks so much for your help. I will be more careful in the future on what filters I buy, and for what seasons. I'm pretty sure that's what caused it after this and other research.

Also, I suspect in the future I'll be replacing that board. The crew that cleaned the ducts and furnace mentioned a problem with condensation...now I think I'll have the confidence to replace it myself when the time comes.

Thanks again all, I really appreciate your assistance...I would have never figured it out on my own.

alexcooper · 03-08-2009, 10:46 PM

Does anyone know where I can download or purchase a service or parts manual for a Goodman GMP100-3 furnace?
Thanks in advance for the help.

alexcooper · 03-09-2009, 09:25 PM

Never mind, I have it. I emailed Goodman and they sent me a PDF copy of the service manual and parts manual.

salmonman · 03-13-2009, 09:47 PM

My heater will not shut off with the thermostat,it runs past the set temp until I have to shut off the power to it.I replaced the thermostat and it worked ok for about a month.Now it continues to run with heat even after I shut the stat.off.This is an older Goodman model R30-08 at least 20 years old.Please Help. Signed overheated in Washington.

**beenthere** · 03-13-2009, 10:40 PM

Look for shorts in low voltage wiring.