Electric Fan Stopped!
I've had a couple of electric fans stop for what seemed like no reason
at all, and all troubleshooting pointed to their having an open winding
and probably not worth fixing. I decided to poke around some, and
found that modern fans are "thermally protected" with a thermal fuse
wired into the motor circuit. These thermal fuses open up when a
set temperature is hit. It is very easy to hit this "over
temperature" limit when there is even a slight drag on the
motor, It seems that a lot of cheap fans must use fish oil
as a lubricant, because I've seen a bunch that bound up for what must
be no reason other than normal use.
So here's what I know. Remember that it's DANGEROUS messing with
things like this. If you mess up, you could electrocute yourself
or burn your house down. Is it worth it?
The fusing is on the common wire to the fan motor. On this one it
was red, and the main wire that didn't run through the switch.
Follow it up, into the motor where it should split out to the starter
capacitor. I think I've seen them on either side of the starter
cap, but this one was right between the common wire and one of the cap
leads, which was also red.
The thermal fuse, and all the other splices are bundled up in high
temperature insulating sleeves. The one with the fuse will be slightly
larger than the others.
The TOUGH part is getting another thermal fuse, and successfully
splicing it into the circuit. Thermal fuses are available at
Radio Shack. The pointy or highlighted end of the fuse is the
more sensitive part of the thermal fuse. Most of the other fans
I've seen had
crimps on the wire so that it wouldn't accidentally get blown when
being assembled. This one was soldered, so I used some large
alligator clips to heat sink between the soldering and the fuse.
Double check the fuse when you're finished and slip the insulation back
around the assembly.
THEN you have to get this mess bundled up, insulated and connected to
the motor frame like it was before. NOT easy, and it could be a
very bad thing if you mess up.
You may want to fix your fan, or you just might want to throw it away
after you've seen what it's going to take to fix it. But at least
you KNOW why it's broken!