Furnace fan always runs

[nonhog]

Not like I don't have enough on my plate,
My In-laws are out of town and the furnace fan wont stop running.
I am hoping to find a manual when I get to there house . Clue as where to start ? Sorry about another half baked thread w/o any real info.
Was just hoping to have some input before I show up over there.
They'll be o.k. with me telling them hire someone, but I dont want to do that if its a simple thing to track down.

 

[sjsfire]

Check the thermostat first, there is a "fan on" switch usually off the side of the thermostat. If the furnace is newer it could be a circuit board causing the problem then. If it wasn't the "fan on" switch I'd call in the pro's.

 

[red98gt]

If it's a newer programmable (digital type) there is usually a setting for "fan on" like the switch on older models like sjsfire said.

Mine has "Continuous", "Circu" and "Auto".

 

[rickairmedic]

Nonhog the others pretty much covered the thermostat if thats not it let us know and I can try to walk you through the other possible causes with a little more info .


Rick

 

[RRmech]

Older furnaces have relays, which can sometimes hang up?


Steve

 

[nonhog]

Thanks guys ! I'll look @ the t-stat but not sure how to confirm its bad other than replace with new one ?

 

[rickairmedic]

nonhog I PM'd you my cell # call me from the inlaws I can walk you through the diagnosis over the phone.


Rick

 

[nonhog]

Got your # Thanks ! I'll start with making sure they did not flip the fan switch on 1st.

 

[rickairmedic]

That'll work if thats not the problem just give me a ring and well walk right through it .

Rick

 

[Torque1st]

Older furnaces have relays, which can sometimes hang up?
Steve

New furnaces have relays on their control boards. The miniature relays frequently go bad.

 

[mulepackin]

nonhog I PM'd you my cell # call me from the inlaws I can walk you through the diagnosis over the phone.


Rick

That is GOOD people there!

 

[kbs2244]

Been a long time since I have had this problem but when I did it was the bonnet temp probe (?) (The thing with the long spring like bi-metal expansion switch.)
It was just kind of dirty and sticking.
I took it out to the garage and cleaned it off with some carb cleaner and compressed air, re-installed it and everything worked fine.

 

[nonhog]

Well It seems to be just switch "fan on" easy fix ! Thanks everybody !
And Big thanks to Rick even though I did not need to call it sure was nice knowing I could have.

 

[rickairmedic]

Nonhog glad it was an easy one . I actually walk my regular customers through a few things on the phone before I drag out to their houses and charge them $60.00 bucks to flip a switch or something silly and I have on occasion walked in flipped a switch and handed them a magnet and told them to call me when they really needed me . I am here getting great info on areas that I dont know alot about so anytime I can help out a fellow member and save them a few bucks to spend on toys I am happy to do it .


Rick

 

[nonhog]

Almost forgot, was in a hurry to get out and race slot cars with my son
Is this a reason for concern ? Corrosion ? white powdery
Furnace about 4 y.o.

 

[rickairmedic]

Nonhog that look to me like the remnants of condensation in the flue pipe . My first question would be how much singlewall flue pipe there is there . I like to run as close to 3' as I can get which is also the max code will allow . I have found if theres not enough singlewall water will condense in the flue pipe due to the flue gases condensing to quickly which happens if the double wall starts to close to the furnace. I dont think is a major concerne but it will lead to the flue pipes rusting out prematurely.


Rick

 

[rickairmedic]

Dan being 4 years old if it vents into a chimney without a liner the Installing company didnt do their job and also most likely didnt pull a permit as that is a code issue. I dont think that model is a 2 stage .

Rick

 

[mikes334]

From the sound of things that is what happened.