furnace fan restarts every 2min


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Old 11-10-15, 08:39 PM
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furnace fan restarts every 2min

Thermostat is set up to reach 73 but furnace doesnt work and current temp is 71 since an hour. Furnace fan then starts for 2mins and turns off. Furnace is making some sounds after that. After a minute furnace fan starts to work again for 2min.
And again the same...
Can you guys help me with this problem?
 
  #2  
Old 11-10-15, 08:48 PM
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If I was there..... I could fix your furnace in a minute. But since I'm not there you need to describe in detail what is happening.

A make and model is always helpful so I know what I'm dealing with.
The stat should start the draft inducer, then the igniter should glow, then the gas should light and the igniter goes out, then the blower should start.

Where is the noise coming from...... down below in the blower area ?
Is the burner staying lit ?
 
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Old 11-11-15, 05:28 AM
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The stat should start the draft inducer, then the igniter should glow, then the gas should light and the igniter goes out, then the blower should start.
If all the steps are taking place as listed above, and the blower is starting but immediately shutting down, it might be just a clogged filter. One thing to confirm or eliminate as the problem.
 
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Old 11-11-15, 07:25 AM
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Name:  furnace.jpg
Views: 235
Size:  50.4 KBHi.
I'm uploading 6min video so you guys can see.
I changed filter couple weeks ago. I'm changing it every 3 months.
When I looked on thermostat in the morning, it shows 73 and it is set up to reach 73. I didn't hear anything.
I switched it to get 75 degrees and went to basement to see it and hear it.
Furnace starts working, buzzer buzzes, fan is blowing but no flame. After 6min I got flame and it was firing for a minute, then fire stops but everything else is working, then again after 1-2-3min fire/flame starts and so on and on.
Then I went to thermostat and switched it back to 73degrees but furnace didn't stop working. And it is still working with fire restarting...

I checked filter, it still looks new, barely grayish...
Here is link to video

I hoped my uploaded video works.
I asked my dad about my problem and he said if it islike i said then it is inducer motor and fan which should never start together...
weird...


Attachment 58669
 

Last edited by trailer-mechani; 11-11-15 at 09:04 AM.
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Old 11-11-15, 09:49 AM
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Your link is to a file hosting site that requires a file download program they supply. I do not access those sites. You'd need to post it on you tube and make it publicly viewable.

You have an intermittent pilot furnace. That means this is the order of events....

Call for heat
Draft inducer runs
Spark ignition lights pilot light
Spark stops and pilot light remains lit.
Main burner lights.
The blower is timer controlled so it will come on whether or not there is a flame.

You have to watch what happens and see where the problem occurs. Usually the pilot won't stay lit. That will mean a pilot assembly cleaning.... including orifice. At this point you are drifting out of the DIY service area and into a gas pro's job.
 
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Old 11-11-15, 01:36 PM
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I was pretty sure you just need to unrar these files.
So this is it? I have to call for a furnace service?

edited
My dad came and he explained me just a little to understand what happens, what to tell you guys.
To turn furnace on I add 1 degree to Thermostat. Furnace starts to work. Inducer motor starts, then we wait 3-6min, then there is flame in burners and a minute later blower on the bottom of furnace starts to blow, then burners stop working and only inducer motor and blower continuously work. Again after a minute or so burners again start to work for another minute and there is a loop...


edited

My dad inspected everything. He said that rubber hose between combustion blower assembly and pressure switch was dirty. He cleaned it and now everything works fine and even burners start to lit faster and they don't stop working.
 

Last edited by trailer-mechani; 11-11-15 at 04:05 PM.
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Old 11-11-15, 04:36 PM
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From the call for heat..... the burner should be lit in a minute or so.

Am I correct in that you have a spark ignited pilot light that then lights the burners ?

If yes.... that spark ignition should start almost immediately after the inducer gets up to speed.... just a few seconds. If that is what is not happening then your problem is/was directly related to the draft inducer. The draft inducer needs to start, create a vacuum on the pressure switch and then activate the spark ignition. That's why I mentioned we needed to know exactly what was happening.
 
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Old 11-11-15, 05:09 PM
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Now it takes about a minute or more but 6x shorter than before.
Am I correct in that you have a spark ignited pilot light that then lights the burners ?
Yes
and then...
hmmm... let me tell it this way:
i dont know when inducer gets up to speed but pilot starts burners after a minute so after quite a while, more than my dad was thinking but he said it still ok in lets say some noirmal time. It is no longer 6min...
 
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Old 11-11-15, 07:13 PM
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As PJ stated. Clean the pilot. I can't see the video, but I presume it is a Carrier product from the description.
 
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Old 11-12-15, 06:41 AM
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Just for you guys!
I converted and compressed this video with MovieMaker and now it's 5 x less.
Here you can download it.
Ypu don't need any kind of other programs, just download my file and watch. It's not even in rar file, it ios just video.
 
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Old 11-12-15, 09:12 PM
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After watching the video I would suggest removing the pressure switch tubing and run a paper clip or small screwdriver in the ports. There maybe a restriction. Also check tubing for cracks. The pilot appears to be clean.
 
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Old 11-12-15, 09:42 PM
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It's not the pilot. It's what happens before the pilot and that's governed by the pressure switch.
In the pic I put an arrow to the fitting you need to clean.

Name:  ps.JPG
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After you do the cleaning like mbk3 mentioned.... give it a try and see if it lights sooner.

If not.... it looks like two wires on the pressure switch. Remove them from the switch. Start the call for heat and then connect them (with jumper). Does pilot system activate quicker ?
 
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Old 11-12-15, 10:02 PM
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This is the exact spot,this rubber hose which my dad cleaned and it helped. Burners start to work a minute after motor. Furnace works fine now.
Thank you all for all help, time and tips.
 
 

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