Ducane Gas Heater, Blower Not Working on Fan Auto, Blows Cold on Fan On


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Old 10-29-12, 01:21 PM
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Ducane Gas Heater, Blower Not Working on Fan Auto, Blows Cold on Fan On

Hi all, nice little group here, been checking some posts, very helpful, so thanks for taking the time to respond if you can.

I've natural gas Ducane furnace in the house. Turned on the heat for the first time since last winter and it looks like I've got a malfunction...It runs, but the blower isn't turning on via auto...Turns on when I set the themostat to manual, but it's then just lightly pushing cold air out of the vents. The blower itself isn't being turned on at all by my thermostat when on "auto" (I assume that's due to it not sensing a temperature increase in the ducts) but blower works fine when turned to "on". But only cold air is blowing.

The furnace is 13 years old and did need service once, but back then it was because the spokes broke inside of the plastic blower wheel assembly. I already took the blower assembly off and verified that's not broken just to be safe.

I don't know much about gas furnaces but I do have an emergency gas shutoff switch as well as the breaker shut off so I feel I can at least safely work around it.

What I don't know is how to tell is the burner is lighting, or where much of anything else such as the "high limit" switch I have been reading about is, so I've attached photo with the plates off. If anyone has any ideas of something simple that a novice like me can check to save myself a service call, would be much appreciated.

Also, I noticed there's a viewing window at the top where an led should be lighting up, however, it doesn't look to be turning on at all, so no luck with an error code.

Up until around a month ago, my AC was working fine via the same system, which is pointing to a problem with the heat itself.

I'm posting some photos in the hopes there might be some easy stuff you fine folks can point out that I can take a look at.

At any case, any help is much obliged, I was hoping to run the heat a little in case I lost power during the hurricane here in the NorthEast!







B.
 
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Old 10-29-12, 05:02 PM
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Since you have easy access to the control board, take a small jumper wire & jump terminals R & W on the terminal strip at the lower left of the board. Leave in on for a couple of minutes & let us know what happens.
 
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Old 10-29-12, 05:06 PM
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Ok,will try -- Leave the existing wires going into them that are already there too, I assume?
 
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Old 10-29-12, 05:12 PM
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Should disconnect the R wire but you don't have to.
 
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Old 10-30-12, 06:30 AM
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Sorry for the delay, had a power outage last night. Thanks for the reply.

I jumped R to W and the system just turned on when I turned power back on, even though I have the thermostat set to off (I assume that's what you expected and this takes the thermostat out of the equation).

I don't hear the blower fan kicking on yet...But I'll let it run a bit and see if anything changes. Without the blower running it's tough to tell if any heat is being generated.

Let me know if there's anything else you'd like me to try, and thank you very much!
 
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Old 10-30-12, 06:36 AM
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Quick update - I heard a click/pop coming from the unit a couple times during the first 2-3 minutes or so of being on (which I assume may be the pilot attempting to light?) but the blower is still not kicking in.

Assume this may be something preventing the gas from lighting (yes, I did flip the gas emergency switch back on ON).

It's been running 5 minutes now, no more clicks, blower fan never came on, no heat detected from vents, so I'm turning it back off.

Anything else I can try that's not too complicated? Or have I hit technician time? Someone else told me I may have a "stuck pressure switch"?
 
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Old 10-30-12, 05:00 PM
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Disconnect the plastic hose from the small venter motor & blow thru it. Sometimes slime will build up over the summer & block it. You can also try tapping on the pressure switch (silver disc right of the venter motor) while the venter is running.
 
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Old 10-30-12, 07:07 PM
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You are the man! One or both of those seems to have done the trick. Powered it back up, flipped on the gas, turned up the heat and I listened to it fire up. Blowing hot air now as it should be!

Thanks so much for saving me a service call. I'll keep a close eye in case it's still flaky, but hopefully that gets us through the winter!
 
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Old 10-31-12, 03:59 AM
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Good deal. Sometimes it's built up crud in the drain, sometimes the pressure switches simply stick. There are multiple causes for a pressure switch to fail to close but those are two of the most common & easiest to fix. Wouldn't hurt to remove the hose from the bottom of the tee where it goes into the PVC pipe & pour in some bleach then replace the hose.
 
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Old 11-10-12, 02:28 PM
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Ducane Gas Heater, Not igniting and blower makes strange loud noises.

Hello, I have tried to cut my heater for the first time since last summer. When I cut it on it had a strange loud noise coming from it as well as the pilot not lighting.

I took the liberty to:

1.replace the air filter
2.replace the igniter
3.vacuum out the system
4.vacuum out the vents

I am wondering if my fan needs to be replaced and if that could be the reason why the burners will not ignite. Please help I am in need of heat as the winter weather is approaching.
 
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Old 11-10-12, 03:34 PM
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It's usually confusing when people add on to an existing thread with a different issue.

I'd suggest reposting on a new thread.
 
 

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