Several weeks back I had the misfortune of having the blower motor go out at my house. The house itself is easily 80+ years old, but the gas furnace/AC unit was retrofitted in 1991 right before I moved in.

The old blower was a GE 1/3rd horsepower 115VAC motor with a full load amp(FLA) rating of 11.9 amps. In my quest for a replacement I found that the dead motor was a shaded pole design. While the design is extremely dated, they are cheap to manufacture but extremely inefficient to say the least.

Finding an equivalent replacement for that dated design proved to be trying at best. I found the "newer" recommended replacement motors in that HP range were PSC(Permanent Split Capacitor) designs that were equally cheap, ~$60ish which was super fine with me. Principle difference in the motor specs was the current(FLA) rating for the PSC motor, which is 6.1 amps, different design and way more efficient.

The guy at the local parts place didn't want to sell me the PSC motor, arguing the difference in current ratings would mean it probably wouldn't work. I tried to explain to him that HP = HP as far as actual work being done, and difference in the design of the motors was the reason for the disparity in motor amps. We ended up agreeing to disagree regarding the current ratings and I bought the motor, capacitor, and adapter bracket, for a total of less than $90 after tax. Took it home, installed it, and yay me, I have AC again.

I installed/fabricated a current monitor just out of curiosity to observe it, and have been looking online at my power consumption. The new motor pulls about 15 amps for a second when starting up which is normal, but settles in at around 5 amps steady state while running. I have no idea what the old motor pulled, but I'm betting it was a lot more than that, 11.9 vs 6.1 FLA rating and all.

Holy cow what a difference in my power consumption. I live in the South, it's hot here, and your AC is the primary driver of power usage. While the weather has been pretty much the same, my cost per day has dropped almost $2/day.

I'm an electrical guy by trade, and I guess I just never put much thought to what was actually in my house... Just thought I'd share...

This message has been edited. Last edited by: stoic-one,