Blower on furnace won't shut off : LUSENET : Freedom! self reliance : One Thread

The blower on my furnace won't stop. I've looked and can't find a reset switch. I hit the breaker, but it came right back on. Called the landlord, but can anyone offer any suggestions? This is a dinosaur gas furnace, probably 20 years old.

-- Cathy in NY (, October 20, 2001


Hey Cath! Sure I know!!! I'm the old "know it all" ya'll know! LOL. It's the mechanical fan switch and it's located on the front of the furnace- in the burner compartment- above the burners. It may be enclosed in a little tin box about 3"wide by about 4 " tall. Depending upon the brand used but most common were the honeywell fan/limit combination. Under the cover will be two switches -if it's a honeywell. Anyhow-these dudes stick sometimes over the summer and have to be "bumped" to release the contacts. If "bumpin" the front of the furncace doesn't release it then a new switch is in order. I'm assuming there is no switches that have turned the blower on-- some furncaces have switches that do that. If so-it probably would be on the fan/limit "box" bottom/top or either side. With more info I might be able to help more. Please email if the above doenst help. Lil Dumplin and the old hick will be gone till later this evening. Gotta go see that "Maddie 'big gurl' gibson today.

BTW-ya'll live too far away for me to make a service call to fix it. LOL.

old hoot. Matt.24:44

-- "old " hoot gibson (, October 20, 2001.

Cathy, Our old furnace, it was here when we moved in, nearly forty years ago, sticks once in a while too. We have to smack it really hard and sometimes more than once, but that does work.

-- Barb Fischer (bfischer42@, October 20, 2001.

Turn off the furnace, let it cool until safe to work close to it. Turn off the electricity to the furnace at the circuit panel/ fuse box. Trace the wire from the blower motor to find the switches, open the switch box cover and look for two metal strips that have a raised contact button about the size of 1/2 of a pencil eraser end. The metal strips their mounted on will be about 3/16 to 1/4 inch wide and about 1 1/4 inches long, they are delicate and springy. Gently spread them apart to see the area where the raised mounds touch, if the raised mounds are burnt away, replace the switch. If the raised mounds are blackened or if there is corrison present; take a long thin strip of fine sandpaper, fold it so that the rough side is out on both sides. Place it between the raised mounds and gently "seesaw" the sand paper until they are smooth and shiney. Make sure there is no dust left behind, reclose the box, turn on the electric and light the furnace. If it still runs continously call a serviceman.

-- mitch hearn (, October 20, 2001.

Cathy: Hoot is right. I had the same problem with an old Chrysler gas furnace. There is a switch connected to a thermostatic spring attached to a shaft which extends into the interior of the furnace above the burners. This causes the fan to continue blowing after the gas jets shut off until the interior is cooled sufficiently. If the blower shuts off at the same time as the burners, you would have serious heat damage to the furnace. What happens is that the thermostatic spring gets old, corroded and starts to stick. I used to have to tap on the cover of the switch mechanism to get it to break loose. If it just won't break loose and you can't get a replacement part, you can override by shutting off power to the blower (should be a switch on the side of the furnace) after allowing sufficient time for the furnace to cool (5 minutes?). There should be a safety feature to prevent the burners from igniting if there is no power to the blower.

-- Skip in WA (, October 26, 2001.


My 30~ year old furnace did that last night. The fan control/limit thermostat was a little bit sticking. The service man hit the control box to release the sticking and the fan stopped. He then cleaned out the bitmetal spring contacts and manually moved the spring contacts several times to make sure that they clicked.

It had been running fine. However, I am looking for a replacement part in case it breaks again. I then can replace it myself without waiting for 3 hours.

-- Ching-Ho Cheng (, February 11, 2002.

Is it danger at all if you'll have to wait for a few days or hours for the service man to come?

-- Felix (, February 10, 2004.

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