my furnace doesn't ignite


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Old 12-13-11, 12:05 AM
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my furnace doesn't ignite

Hi all,

I see a lot of posts here about furnace not igniting, but not completely sure which one applies to my case.

I set thermostat to 70F to start the heat. But all I heard was "ahahaah", but no ignition, no fan..no nothing. It ah for awhile then stop.
I tried turning the switch on and off, but the same thing happened.
Is it the ignition problem?

My furnace is made by International Comfort Product
Model:
GNJ075M12C3
Serial
L980484595
Your help is greatly appreciated...
Happy Holiday.
 
  #2  
Old 12-13-11, 06:15 AM
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Take the cover off the burner compartment. Carefully observe the sequence of events that occur when the thermostat is turned up to call for heat.

In particular, you need to describe where this noise is coming from.


Is there a small motor above the burners that is trying and failing to switch on which is causing the noise?
 
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Old 12-13-11, 09:12 AM
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Yes, you are right..it's the motor above the burners. It's making "ahah" noise but doesn't start. Then stop making noise after some minutes.
Is it the first thing that runs in the start sequence? what could be wrong with it?

thanks
 
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Old 12-13-11, 10:04 AM
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i did some more searches..it seems like a dead capacitor 'cause it's not turning the motor on..
is that right?
 
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Old 12-13-11, 10:10 AM
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If there is a capacitor connected to the inducer motor, replacing it might be worth a try.

It's more likely that the cause is that the bearings have failed, making the motor hard to turn and causing the noise. It's probably possible to removed the inducer motor assembly without too much trouble to check on that as a possible problem.
 

Last edited by SeattlePioneer; 12-13-11 at 10:41 AM.
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Old 12-13-11, 11:01 AM
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In our case, just last week, we found where a rodent had chewed a hole in the rubberized tubing running to the combustion blower pressure sensing switch. Fixed it, but didn't install traps. A couple days later, on a morning when we hit minus 16F and woke up to a 40F house, the little <bleep> had repeated but this time with two holes. Fixed it, installed traps. No repeat, so far. Our furnace is mounted beneath the house in the crawlspace. Haven't felt the need to go look to see if we caught anything, mostly because it's a PITA to get under there, even in warm weather.

Point is, don't rule out all possible causes by assuming a particular fix should work.
 
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Old 12-13-11, 12:44 PM
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My furnace doesn't ignite

Our gas forced air furnace wouldn't ignite at the begnning of the heating season either. I looked through the manual and followed the steps for shut down and restart. It required a few steps, but it worked. I guess these steps are for those who want to shut their furnace down completely in order to run the AC in the summer.
 
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Old 12-13-11, 12:57 PM
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it keeps making a humming noise. I turns off heater and turn on the fan, and that works fine
1. there's power coming into the motor. But the motor can't start. It just hums
2. there's no power coming into the motor.
 

Last edited by den007; 12-13-11 at 01:36 PM.
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Old 12-13-11, 06:24 PM
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You need to replace the inducer motor assembly.

Usually that is sold as a kit which includes a new motor, fan gaskets and such--- all the parts needed. I'd buy that assembly if it's available, since that will make installing the new part easier.
 
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Old 12-13-11, 08:15 PM
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i finally found the problem.. it's the blower motor.
It tried to rotate but stuck somewhere. I took the motor out, put it back in. It worked, but then after awhile, it stopped again. I could hear it slowing down with a squeal noise just like riding a brake in a car.

why does it do that after awhile?

thanks,
 
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Old 12-13-11, 09:29 PM
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Are you talking about the fan motor which circulates air around the house? That's what's not starting?
 
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Old 12-13-11, 09:38 PM
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no, it's not.
it's the blower above the burners
 
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Old 12-13-11, 10:02 PM
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OK. That's called the inducer motor, inducer fan or inducer fan assembly. It creates a negative pressure which sucks the combustion air and combustion gasses through the furnace.

I wanted to be sure we were talking about the same thing.
 
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Old 12-13-11, 11:15 PM
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oh great..i have been looking for that name. Thanks, Seattle
Funny thing is I have to do some screw adjustment to get it started.. but then it stops after awhile.
losing some hair over this..
 
 

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