Hello all. I originally posted this in alt.hvac but they pointed me here.
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.
Thanks. Bill