Goodman GMH95 Fan/Ignition Issue


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Old 11-26-13, 08:53 PM
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Goodman GMH95 Fan/Ignition Issue

Hello,

I have a Goodman GMH95 that I just replaced the induced draft blower after a bearing in the motor seized. After replacing the induced draft blower, there are two behaviors which I cannot trouble shoot further without more experience.

Either:
- Induced draft motor starts, runs for about two seconds, then powers off. Repeat. Main board LED stays solid, or is off if the induced draft motor is off.
- With pressure switch hose disconnected, induced draft motor starts, runs, but furnace does not light. Main board LED blinks three times.

The manual suggests this means:
• Pressure switch hose blocked, pinched or connected improperly.
This not likely as sucking the hose creates the above described condition, and I hear it click.
• Blocked flue and/or inlet air pipe, blocked drain system, or weak induced draft blower.
No idea how to confirm this. One of the induced draft motor bearings seized, and the whole induced draft blower has been replaced.
• Incorrect pressure switch setpoint or malfunctioning switch contacts.
This has not been changed, and it still shuts off when sucking the hose, so this seems unlikely.
• Loose or improperly connected wiring.
This has not been changed, and it still shuts off when sucking the hose, so this seems unlikely.

Does anyone have a suggestion about how to resolve this issue?
 
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Old 11-26-13, 10:52 PM
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The tube has to be connected for the pressure switch to close.

Are you sure that you used the right inducer assembly for your furnace? (I'm not 100% sure on this, but either there's a separate assembly for each furnace size, or there's something you have to do to the inducer before installing it - check instructions which came with the inducer)

If you have a multimeter, check the voltage across the pressure switch when there's a call for heat. Leave the wires connected and whatever you do, never bypass any safety. (0V = closed, 24v = open)

If you can't figure it out, call for service; that furnace may still have a parts warranty on it.
 
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Old 11-27-13, 07:35 AM
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Yes, it is the correct part. I thought it was odd that it ran, and the hot surface igniter would come on with the tube disconnected. The tube itself passes air with no issues, having removed it, and blown through it with no issues or debris being expelled. Sadly, I do not have a voltmeter to test further at this time.
 
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Old 11-27-13, 06:44 PM
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Did the blower come with any odd looking adapter plates ?

You said it's the correct part. Does that means it's the exact same part number that was in originally or that it is the correct substituted part ?

Some of the substitution blowers require an adapter plate that may or may not be supplied with the blower.
 
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Old 11-30-13, 12:44 PM
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The draft inducer did not come with any extra parts, and was the same part number. The issue has been resolved, and was a stuck pressure switch.

Thanks for everyone's feedback.
 
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Old 12-01-13, 05:01 PM
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how did you determine it was a stuck pressure switch? I am having a similar issue 3 blinking lights which I was about to post about when I saw this thread.
 
 

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