View Full Version : Burner lights, but fan won't blow

Dec 12, 2006, 07:59 AM
Day & Night gas (NG) furnace
Carrier 800-19A on stamped ID plate
Forced air

We just moved in. The furnace has worked just fine several times. We keep the thermostat on the lowest setting, manually cranking it up for those few times that we need heat here in southern California.

This morning, I turned up the thermostat, heard it click, but the furnace did not turn on. I verified that it 1) had power, and 2) the pilot light was properly lit. After futzing around a bit (I really didn't DO anything), the burners kicked on. GREAT!

After a couple of minutes, the burners just turned off. The fan/blower never kicked on.

With the thermostat all the way up, the furnace cycles through the same [incomplete] process. Why won't the blower kick in?


Dec 13, 2006, 11:25 AM
I tried it again this morning and experienced the same. The blower simply doesn't turn on. What determines exactly when the blower's motor kicks in gear? Might the motor (http://bestbuyheatingandairconditioning.com/Merchant2/merchant.mvc?Screen=PROD&Product_Code=MOT6281405&Category_Code=M) be burned out?

Correction: The unit is a Carrier 80U-19A, not an 800-19A.

Dec 13, 2006, 10:52 PM
There is a blower control located in the furnace. More than likely it is the problem.

Dec 14, 2006, 04:21 AM
If you just bought the house, the seller is obligated to have things like the furnace in operating shape. Call them and let them pay to have a service man. Wouldn't hurt to have the furnace inspected for other defects such as a cracked heat exchanger.

On older furnaces the blower started after a limit switch heated up. Newer ones it is a timed delay on the circuit board. In either case, the switching is done by a relay when the coil is activated. Yes the blower motor could be burned out. Before replacing it, make sure it doesn't run when it has power to it. It is much cheaper to identify the bad component, and replace it first. Replacing the wrong thing first wastes money and doesn't solve the problem.

To do simple checks like this you do need some tools. A test light, a meter, or a voltage detector might be the best place to start with. I came across the niftiest gadget for trouble shooting, a voltage detector. They work through the insulation of wires. There are several brands. I have a GB Instruments GVD-505A, less than $15 at Home Depot. Touch it to a hot wire, and the end glows red. Find the doodad that lights it on one side, and not the other, and you have the culprit. You do not have to open up housings and expose electrical contacts. You are looking at where your hand is, not where the meter is. Most people are capable of doing repairs and will get it going and not get hurt if they use a little sense. The voltage detector makes it even easier.

Dec 15, 2006, 08:38 AM
Thanks to both of you for your quality feedback. It looks like we're covered by a formal home warranty program that was part of the purchase deal. I'll be placing a phone call today to see what can be done about fixing the furnace.

( = c h e e r s =)