Hello all. I originally posted this in alt.hvac but they pointed me
Two years ago I had to replace my furnace but I kept the old
fan. Last year I built a frame around the fan and installed it in my
attic. I figured that this type of fan would be quieter than the
standard whole-house attic fans you see at Home Depot.
It worked great for a year but now has a problem. It's a three speed
fan with four wires: one neutral and one for each speed. I had wired it
with a three speed fan switch. The problem is that now only the low
speed works. It runs when I switch it to mdeium or high, but still on
the low speed. When I switch it to high, the pitch is just slightly
different. Does this mean that the other windings are fried, or is it
possible to fix this easily? I know very little about how multispeed
motors are wired inside.
Any help would be appreciated.