Goodman heater error code 3 (pressure switch stuck open)


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Old 11-08-14, 10:46 AM
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Goodman heater error code 3 (pressure switch stuck open)

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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Old 11-08-14, 11:00 AM
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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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Old 11-08-14, 02:58 PM
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Thanks, I'll read through that document. It's a brand new inducer and I've already checked the hose.
 
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Old 11-08-14, 03:23 PM
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It's a brand new inducer
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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Old 11-08-14, 05:43 PM
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The inducer motor was replaced a few months ago during the summer so it was only ran for a few minutes. I completely removed the vent above the inducer to take a possible blockage out of the equation with no success. I'm stumped.
 
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Old 11-09-14, 11:00 AM
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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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Old 11-09-14, 11:21 AM
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I appreciate the brain storming. No condensation in the tube but I'll shorten it. Pressure switch was bought online. I still have the original one, my next attempt to fix it was going to put the original one back on (it's at a rental of mine that is about 45 minutes away). There was a type of a high heat seal that came with the inducer. Installation of it was pretty straight forward.
 
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Old 11-09-14, 12:02 PM
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In my experience, pressure switches rarely fail. It is usually just doing it's job and functions as expected due to some other cause other than a defective switch. Another possibility is that you could have a crack in the heat exchanger.
 
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Old 11-09-14, 01:51 PM
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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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Old 11-09-14, 02:23 PM
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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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Old 11-21-14, 05:38 AM
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pressure switch open

I had the same issue this morning. Followed all the advice from this and other forums. All checked out, was getting ready to pull fan out to check internals and when I tried to disconnect one of the motor spade connectors, it came off in my hand. Replaced the spade connector and now all it good. The symptom I saw, the motor would try to start for about 1second, then stop, retry and eventually it would start. After the fix, it start first time.
 
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Old 11-21-14, 08:36 AM
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I meant to give an update...After replacing the inducer motor I had left the new pressure switch installed. I put the original pressure switch back and it's working great now.
 
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Old 11-21-14, 08:51 AM
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Glad to hear your furnace is operating properly and thanks for the update!
 
 

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