Goodman Limit switch questions

Posted by Bubba on April 22, 2009, 9:12 pm

On Wed, 22 Apr 2009 20:19:21 -0400, "Stormin Mormon"

>Hmm. Customer who knows how to jump out limit switches. Yep,
>you're dangerous. Glad your furnace is fixed.

Almost as scary as a "Stormy" knowing how to jump out a limit switch.
Good thing Stormy isnt that bright.
Bubba

Posted by Lefty on April 22, 2009, 7:09 am

> So I come home today and crank up the thermostat a few degrees and get on
> with dinner prep. That's weird, it sure seems a bit chilly when I sit
> down to eat my dinner...
> Go over to the thermostat, and see that although I hear the blowers
> blowing, the red light on the thermostat is not on as it usually is, and
> cold air is blowing out the vents.
> Trudge downstairs, thinking "ignitor". Poke around there a little, pull
> the ignitor but it's solid. Look in the bottom half of the furnace, and
> read the "diagnostic" chart, that tells me what the status light on the
> circuit board means when it flashes. Re-apply power, both blower fans go
> on, but no ignition, and the light is flashing 4 times. The chart says
> that means I have an open limit switch. Apparently there are two? a main
> and an aux. Try to follow the schematics, and my best guess is that the
> main limit switch is connected on red wires, and goes into the plenum.
> Pulled it out, and it looks like a tiny little metal drum on a probe, yes?
> There are 3 other little drums that are in the front of the furnace, kind
> of flush with the bottom, and each has little switches connected to them.
> I pressed each one a few times, but that didnt' make a difference. Light
> purple wires on those. Aux Limit Switches?
> how much more can I DIY before I call in the big guns? Looks like the
> mail LS runs about $35? Worth it to just change it out?
> this is a Goodman GMP125-4, I'm thinking circa 1996, since the SN starts
> with 96.
> thanks for any tips/info.

I'd call pro.
It's spring you know. Birds could be dumping grasses down the flue in an
attempt to build a nest (or just end your life, according to Hichcock sp?).
Of course, you did say Janitrol/Goodman. It prolly requires a board, like
every other Goodman out there. But don't try jumping out limits without
verifying what they sense to begin with. And you do know they are prone to
the overclamped heat exchanger manufacturing issue right? Like I said, I'd
call a pro.

Posted by Bubba on April 22, 2009, 7:42 am

On Tue, 21 Apr 2009 22:06:10 -0500, "barbie.gee"

>So I come home today and crank up the thermostat a few degrees and get
>on with dinner prep. That's weird, it sure seems a bit chilly when I
>sit down to eat my dinner...
>Go over to the thermostat, and see that although I hear the blowers
>blowing, the red light on the thermostat is not on as it usually is, and
>cold air is blowing out the vents.
>Trudge downstairs, thinking "ignitor". Poke around there a little, pull
>the ignitor but it's solid. Look in the bottom half of the furnace, and
>read the "diagnostic" chart, that tells me what the status light on the
>circuit board means when it flashes. Re-apply power, both blower fans
>go on, but no ignition, and the light is flashing 4 times. The chart
>says that means I have an open limit switch. Apparently there are two?
> a main and an aux. Try to follow the schematics, and my best guess is
>that the main limit switch is connected on red wires, and goes into the
>plenum. Pulled it out, and it looks like a tiny little metal drum on a
>probe, yes?
>There are 3 other little drums that are in the front of the furnace,
>kind of flush with the bottom, and each has little switches connected to
>them. I pressed each one a few times, but that didnt' make a
>difference. Light purple wires on those. Aux Limit Switches?
>how much more can I DIY before I call in the big guns? Looks like the
>mail LS runs about $35? Worth it to just change it out?
>this is a Goodman GMP125-4, I'm thinking circa 1996, since the SN starts
>with 96.
>thanks for any tips/info.

Just jump out all those stinkin limits. No need for them. Just a bunch
of silly extra parts they add to a system to raise the price of the
unit. If the filter is dirty, just pull it and dont put in another.
Your system doesnt need one. Its made of metal. Why does it need some
silly spun fiberglass material to protect metal??
Bubba

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Goodman Limit switch questions - Page 2