Furnace turns off but then back on again briefly

[Francheezie]

Unfortunately I am without any of the furnace documentation and this is my first house/furnace. I have see pictures of a Fan Control for a carrier online, however, I am unable to locate mine. Can you please help me find it? Thank you.

[tom12345]

Well I got back to looking at the furnace again last night.

After I unscrewed the vent control safety thing to look at the part number a couple of days ago. I have it a quick cleaning by blowing the dust off it. The furnace after 1 run on started working properly again. After a day or two back to the same old problem. But I'm only having 1 run on not the 2 like I was having before.

I looked through the paper work again and I see no manual adjustment for the fan control.

I opened up the cover for the circuit board and saw no adjustable controls in there. Just a bunch of resisters, caps and 2 big relays. No adjustsment to me can be made in there.

I'm at a loss. I have an older Maple Chase digital thermastat. I can't believe it's that though.

Tom

[Hube]

Tom; Some units do not have adjustable controls, just replaceable parts. check with your Tech, as to your make and model. Hube

[tom12345]

Well, The furnace is working properly now.

I ended up looking at the thermostat, and this is what I did. I pushed the reset button on the thermostat to clear all settings.
Then, I recalibrated the thermostat. It was 2 degrees off. Then there's a switch in it which tell the furnace either to turn the fan on with a call for heat or will allow the furnace to use it's own biult in delay.
I operated the slide switch back and forth about ten times to clean the contacts incase there was a build on the copper tangs. Put it back in it's original position(furnace turns fan on with delay).
I set the setback to 4 degrees.
At this time it's been cycling off properly for a day and a half now.
Hopefully this seemed to clear the problem, but only time will tell.
Hube, Thanks for all your replies I appreciate them.
Franch, good luck, I hope you find a solution.
Tom

[craigcnatl]

i have a lennox furnace. when i turn the theromostate to heat i can hear the flames start for a few minutes but the blower doens't come on. a moment later the flame stop. does anyone have an idea what the problem could be?

[Francheezie]

Turns out I needed a new Fan Control board. Fixed it right up. There were no replaceable parts on the old board (without soldering).