Gas furnace not lighting


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Old 11-04-09, 04:25 AM
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Gas furnace not lighting

I have a Goodman Manufacturing Co. model # GMNT080-4 gas furnace that's probably about 4 years old. When I turn up the heat the initial motor/fan kicks on, but, the pilot doesn't light. The pilot is an automatic one and there's a warning label that says not to manually light it. I replaced the fuse because something similar happened previously and that's what it was. I had the furnaced cleaned about a week and a half ago. Any help would be appreciated.
Thanks!
Amanda
 
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Old 11-04-09, 04:37 AM
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Cleaned

If the furnace was serviced that recently, I'd call the servicer back.
 
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Old 11-04-09, 06:15 AM
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Originally Posted by Grady
If the furnace was serviced that recently, I'd call the servicer back.
With last bill in hand..........................
 
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Old 11-04-09, 07:53 AM
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By the motor/fan I'm supposing you are talking about the inducer motor.

Before the spark and pilot gas would turn on, there's probably a pressure switch that needs to close. Very likely that's where the problem is. I'd check for the presence of 24 VAC on the pressure switch to see if that's signaling a problem.

Also, the port on the inducer motor housing where the rubber tubing from the pressure switch can get plugged with corrosion. Remove the rubber tubing and try cleaning out the hole with a very small drill bit.

Check for any blockages of the drain system for the furnace.
 
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Old 11-04-09, 03:20 PM
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my 2 cents worth

I had similar problem with mine, and luckily it was only that the vacuum hose between the exhaust fan and the vacuum relay (not sure of exact terminology) had come loose. I clipped off the swollen end of the hose and reattached it. Worked fine. Yea!

Perhaps your serviceman inadvertantly knocked your hose loose? (Not hard to do.)

It is also possible your pilot element has failed and needs replacing. A new one costs $25-$50, plus labor to install.

Background:
The exhaust fan comes on when the thermostat kicks on. That is probably the fan you are hearing. When the exhaust fan comes on it creates suction which is transmitted down the vacuum hose to the relay. The relay is then sucked closed, supplying voltage to the gas valve & pilot element. The gas valve then opens supplying gas to the furnace. Simultaneously, voltage is supplied to the pilot element to make it glow and ignite the gas. The vacuum acts as a safety feature to prevent the furnace from operating if the exhaust fan fails. Otherwise carbon monoxide could build up and kill everyone in the house. Yikes!

There is a timer that will shutoff voltage to the gas valve if the pilot fails to ignite the gas. Again, this may be your problem, if your vacuum hose is ok.
 
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Old 11-04-09, 05:13 PM
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Originally Posted by materursa
I have a Goodman Manufacturing Co. model # GMNT080-4 gas furnace that's probably about 4 years old. When I turn up the heat the initial motor/fan kicks on, but, the pilot doesn't light. The pilot is an automatic one and there's a warning label that says not to manually light it. I replaced the fuse because something similar happened previously and that's what it was. I had the furnaced cleaned about a week and a half ago. Any help would be appreciated.
Thanks!
Amanda
What did he clean, and what kind of bill did you get?

And did the furnace successfully run many times since he did the cleaning job? (Trying to find out if his being there was merely a coincidence regarding the future problem you now have). Did you have the furnace cleaned just for routine maintenance, or was the furnace acting up? And did you use a reputable company that you do not think would have planted something to maybe go wrong (so they could make more money off you), knowing they are dealing with a female?
 
 

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