Blower Fuse Keeps Blowing

5 years ago

I've had a problem for about 5 years now. Typically it happens at the start of summer, and I always thought it was because I was lazy about replacing my AC filters. But every year I started having my AC go out, with the thermostat turning off. Each time, I called someone and they'd come out and tell me a fuse connecting the furnace had blown. I'd never actually been up in my attic, so each time this happened I relied on bringing someone out to take care of it. Finally, when it happened this year I had the guy do some diagnosis. He thought the fuse receptacle was burned out. So he replaced that and put in a resettable fuse/breaker (and finally I got up in the attic myself and realized its not that big a deal to get up there). When it blew again, another guy came out and said the blower motor capacitor could be bad so he replaced that. After he replaced that I went through a period where the breaker was tripping every 1-5 days, and I just reset it myself. Now, it's gone for about a month without tripping.

The fuse/breaker is 15A and this is on a 20A circuit (the breaker on my electrical box has never tripped).

At the same time, I think that my electrical bill might be growing larger than it should (I'll post a separate question about that).

Has anyone seen this behavior of the constantly blowing blower fuse/breaker? I've now had two AC guys not find the root cause. Any suggestions?

Sort by:Oldest

Comments (2)

outpaientzero
5 years ago
I'll speculate with questions.

Is the blower motor the only thing connected to the 15 amp breaker?

If so it could be simply a dirty squirrel cage caked up with grease crud and dirt. Check it and clean it.

IF the motor is old it may have bushings that require oiling. Many older motors have little oil holes on both ends of the motor shaft and a few drops of light weight oil will help. If there are no oil holes (or even if it does) turn the blower shaft by hand, it should turn easily and slowly coast to a stop. If turning it is hard with resistance the bushing/bearings are bad and the motor needs replaced. Wiggle the motor shaft, if it wobbles up and down on the bushing/bearing replace the motor.

You say a capacitor was replaced? And the guy just maybe, not sure, just a guess, thought it was the problem so he replaced it. The guy didn't know what he was doing and any good service guy would know how to troubleshoot a capacitor and know if it was bad.

Here is what I'd do. I'd clamp the motor wire with an Amp meter to see how much amperage it's using and compare it to the motor name plate. The motor should pull a couple of amps, (the motor label plate will tell you what it should be). If it's pulling 5, 10, 12 amps you just found out why you electric bill is $1000. Your motor may have more than one capacitor. A run capacitor for sure and maybe a start capacitor. A bad start capacitor usually will blow a fuse, but a run may not and cause the amperage draw to go way up.

Find someone who knows what the heck they're doing, your problem should have been fixed 5 years ago.
Eric Solberg
Original Author
5 years ago
I think you're on the right track. I think the last AC guy did measure the current and if I remember correctly he said 12A. As far as I know, he didn't compare that to the rating plate, but rather just noted it was under the current to trip the breaker. I feel kind of dumb to take this long to put it together, but at least its something to work toward a solution. Thanks for the input.
Related Professionals
Richmond General Contractors · Frederick General Contractors · Mansfield General Contractors · Dodge City General Contractors · Sarnia General Contractors · Lexington Home Remodeling · Athens Home Remodeling · Bennington Home Remodeling · Bismarck Home Remodeling · Decatur Bathroom Remodelers · Sarasota Bathroom Remodelers · Albany Bathroom Remodelers · Rochester Bathroom Remodelers · Cleveland Bathroom Remodelers · Sheboygan Bathroom Remodelers