Goodman heater error code 3 (pressure switch stuck open) (2024)

11-08-14, 10:46 AM

I've got a Goodman 80% efficient heater that was installed in 2008. Towards the end of the winter season last year it started giving an error code 3 (pressure switch stuck open). The flames wouldn't ever ignite if I remember right. If I shorted out the wires attached to the pressure switch it seemed to work fine. I temporarily disconnected the vent above the inducer to rule out a blockage restricting airflow...no change. I tried a new pressure switch with no luck. A few months ago I got a new inducer motor on warranty and it seemed to fix the problem.

I turned on the heater a few weeks ago to make sure it was really fixed and now the flames ignite and after a short while they turn off with the same error code 3. I'm really at a loss where to go from here. Any advice?

Model GMS80704BNBD

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11-08-14, 11:00 AM

Welcome to the forums!! Here is a link to a manual for your furnace that contains a troubleshooting guide starting on page 29:

http://www.alpinehomeair.com/related...structions.pdf

As a start, I suggest you remove the pressure switch hose and make sure it is clear from end to end. While the hose is off check the port where the hose attaches to the inducer. Sometimes crud builds up in the small hole and prevents proper operation of the pressure switch. You can use an opened paper clip to ream it out.

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11-08-14, 02:58 PM

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11-08-14, 03:23 PM

You stated you replaced the inducer last year and then operated the furnace. It doesn't take long for crud to build up in the inducer port. I am attaching an excerpt from the fault code list that shows possibilities to produce a 3 flash code.

Have you checked the vent pipe this season to ensure there is nothing inside it to restrict or block it such as a bird's nest, wasp nest, leaves, dead animal, etc.?
I have found dead birds and other garbage inside inducer motors that caused an issue such as yours.

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11-08-14, 05:43 PM

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11-09-14, 11:00 AM

Trying to think of other possibilities:

1. When you replaced the inducer motor was the gasket replaced also? A leak at the gasket will prevent enough vacuum to close the pressure switch.

2. When you replaced the pressure switch was an exact oem replacement switch used?

3. How is the hose from the inducer motor to the pressure switch routed? If the hose is too long and forms a "U" (like a p-trap"), moisture can build up and prevent the pressure switch from closing. If that is the case, the hose can be shortened.

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11-09-14, 11:21 AM

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11-09-14, 12:02 PM

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11-09-14, 01:51 PM

Yeah, I've also read that the pressure switch is rarely the cause for the code 3 errors. That was the first thing I tried before replacing the inducer motor so I was wondering if I replaced it with a non OEM faulty switch. I still have the original so I was going to put it back.

My fear is it's the heat exchanger. From my research it as the Goodman GMP models that have notoriously bad heat exchangers right? If mine is bad is there a way to diagnose that without taking the heater all apart? I'm assuming the heat exchanger replacement is a pro only job? I'm pretty handy and if I had some instructions I might be able to replace it.

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#10

11-09-14, 02:23 PM

I have never worked on a Goodman furnace with that particular heat exchanger.

Here is a link to the parts manual for your furnace: http://www.alpinehomeair.com/related...s%20Manual.pdf

Refer to M10 for your model. Page 12 shows the breakdown for the heat exchanger (#61) and what is involved to remove it.

The part number of the heat exchanger is 4021308S.

Here is a link to some info about your furnace: http://www.alpinehomeair.com/related...%20Furnace.pdf

The third page shows the heat exchanger configuration and states it has a lifetime limited warranty on the heat exchanger.

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#11

11-21-14, 05:38 AM

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#12

11-21-14, 08:36 AM

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#13

11-21-14, 08:51 AM

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