I have a 80% GMH8 goodman furnace that won't ignite. I can manually light it when the gas valve opens and it will run fine and shut off like normal. The glow plug ignitor doesn't come on but a couple of times I have saw it glow for a sec then go out way before the gas valve opens. The furnace was recently installed and we had to put a new circuit board in it when we installed it in the summer. Could it be the ignitor even though its came on a for a sec a few times? Any help would be greatly appreciated!

Welcome back rocky, I believe you may have a faulty glow plug. You can light it manually every time yes? If so , you most likely have a bad glow plug, kind of like a light bulb that work once in a while, or (hopefully not) a bad control board. Lets hope for some more input on this subject,

Hvac, are you out there,

Yes you can manually light it every time with no problem.

Remove glow plug, look at it very closely, if there is a very white spot on the plug, or you see any gap(crack) on the plug, you need to replace glow plug.

I pulled it out and I can't see and bad areas on it, it actually looks like new, could it still be bad even though there isn't any obvious damage?

I`ve never had a igniter to work once in a while or even for a sec. once in a while,, you can do a continuity test on it, if it looks good and tests out,could be something isn`t telling it to ignite

Is there anything other than the board that would tell it to ignite?

Is it flashing a code at the board?if the pressure switch doesn`t since enough negative. Pressure it will not allow it to ignite

There is a slight chance that the HSI does have a hairline crack but still have continuity. When voltage is applied the HSI could vibrate ever so slightly but enough to break that continuity. It's a slim chance but I have seen it.

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Originally Posted by wmproop

is it flashing a code at the board?if the pressure switch doesn`t sinse enough neg. pressure it will not allow it to ignite

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If the pressure switch wasn't making then the valve wouldn't open and the poster mentioned he could ignite the unit manually.

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Originally Posted by MarkwithaK

If the pressure switch wasn't making then the valve wouldn't open and the poster mentioned he could ignite the unit manually.

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Right,, needed to re-read the post,, yes I did,, but still doesn`t seem right that the gas valve is opening up without the igniter lite first

Quote:

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Originally Posted by wmproop

right,,,,needed to re-read the post,,,,,,yes I did,,,,,,,,,,,,,,but still doesn`t seem right that the gas valve is opening up without the igniter lite first

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That is typical sequence of operation. The HSI gets voltage and the valve will open if the igniter works or not. If the unit doesn't fire then that is what the flame sensor is for. No flame sensed then the valve is closed.

Yes after it goes through the ignition cycle a couple times the light on the board does flash, it's a slow continuous blinking. And yes it does run fine after I manually light it with a bbq lighter.

rocky21

(((Here is a post from the same problem you had on Oct 18-19 2008)))

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i have determined that the problem lies with the glow plug ignitor. i did see it glow once when it was trying to cycle but as quick as it came on it went out and it seemed like it came on too early. if you manually light it it will cycle just fine, runs till the desired temp and shuts off normally.


Now you are back on Nov the 11th with the same problem?

What is up with this? I am sure by now you have replaced the ignitor you said was the problem back in the older post.

Here is a link to your older post first page.

https://www.askmehelpdesk.com/heatin...te-270833.html

No I called the installer as was suggested, but it's a warranty issue and he doesn't have time to do warranty work for free, so its still not working. Just trying to get it back in working order.

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Originally Posted by rocky21

no i called the installer as was suggested, but its a warranty issue and he dosent have time to do warranty work for free, so its still not working. just trying to get it back in working order.

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Doesn`t have time!! I`ll bet he had time when he was standing with his hand held out for you to fork over the big money when you got installation done,, most do have to charge labor but the part under warranty doesn`t cost him anything,, sorry but its people like that ,that gives the HVAC contracters a bad name ,

I know and after spending so much money I'm just trying to save and fix it myself, I work on cars houses just about anything I can fix if I study it a bit. Should I get another ignitor and try that or do you think it might be the board again, or could it just be a bad connection somewhere?

Check your connections. If you have not replaced the ignitor check to see if voltage is available to the ignitor when the heat is called for. If power is available and the ignitor does not glow then it has to be defective.

Hvac said it. Check for 120v at igniter, if 120v and no glow, replace glow plug. If no, or low voltage at glow plug, sounds like a connection, or board. Do you have any idea how to check for correct voltage at igniter?

How old is your furnace. If it is less than a year, the installer should fix any problems for free. If over a year, you will only pay for labor. Either way, you had a lousy company install your furnace, if they say they are to busy to take care of a heat call. They shouldn't be installing furnaces is they can't make time to work on them. Just an opinion, but I'm sure most would agree with me.

I'm not 100% sure on how to properly check the voltage, I do have a multitester, not real sure what setting to set it on or how to check it properly. And yes the furnace is less than a year old it was started in the beginning of July and finished instillation about the middle of August.(yes it seemed like a long istall to me too)