Monday, May 28, 2012

Compressor Fan

Its Memorial day, 95 degrees Fahrenheit outside, and the Air Conditioner quit working.  We knew that the Compressor Fan motor bearings were dying, making squealing and grinding noises.  Well last night (Sunday) it quit running.  No way to get parts on Sunday night, and today is Memorial Day so none of the Industrial Supply places are open.  Last week we had the air Conditioner company give us a quote to replace the Compressor Fan motor, and it was $670!  We decided to wait until the motor failed.
No Air Conditioning makes some people in my house very cranky.  So I really needed to get this fixed pronto today, and had to find someplace that was open who would have a quarter horsepower, single phase, AC motor.  Turner Hardware in Farmers Branch came to the rescue, again.  They had the right motor, and the matching capacitor it needed.  This is a universal motor, so it required that I modify it a little for this application.
I needed to trim the case bolts, and also cut the shaft to the length on the original motor.  It was fairly easy to trim the case bolts and the shaft with a hacksaw.  The motor is mounted from the backside, and the shaft points down when its mounted in the Air Conditioner chassis.
There are four wires that go to the electrical control box, a ground wire, and a couple of wire to control the direction of rotation.  It is a proper replacement, so I didn't need to alter the mounting, and it fit the same holes.  There is a conduit which routes the AC wires away from the fan.  The ground wire needed to be attached to the chassis in close proximity to the motor.  I used a sheet metal screw to secure the ground wire to the sheet metal frame.  I used a couple tie wraps to secure the direction control wires to the louvers on the top of the assembly, keeping them away from the fan.
After the motor and wires were secured I fitted the top back on the rest of the Air Conditioner, and secured it with its screws.  I would up taking to unit apart and putting it back together a couple of times because I had the rotation wrong.  It was turning the fan counterclockwise, and should have been turning clockwise.  This is a simple change, by reversing the rotation control wires, but you have to take the Air Conditioner top off again, change the rotation control wires, and then put it back together again.
Then the last step is to wire the new motor into the control box.  This new motor was a little different than the units original wiring.  This unit had been modified by service people before, so its not quite the same as the wiring diagram posted on the unit from the factory.  Between the wiring diagram on the motor, and the wiring diagram on the Air Conditioner I was able to get it hooked up right, and working.  I only paid $130 for the motor at Turner Hardware, which is only about 20% of what the Air Conditioner guy wanted for his repair.  I did also have to buy a 5 uF Capacitor, which was $15.  I took about four hours total to make this repair, and now we're cool again...


  1. Good post, of course! Thanks! As the electricity bills are soaring up, it is essential to be aware of utilizing energy in an efficient manner.

    Air Conditioner

    1. Howdy Juliette,

      Mo Efficient is Mo Betta...

      Ultimately I would redesign this system with a permanent magnet motor, and put the compressor and fan on the same shaft to simplify things. Nice to see someone besides Anonymous posting replies on my blog...

      Goodwill to All, for All is One...

  2. Nothing like having the skills, knowledge, and tools to fix it yourself in an emergency. Our survival odds increase the more capable we are of doing many different things. Your wife is very lucky to have such a man around!

    1. Zup dog,

      Mad skillz, Yeah, I haz them...

  3. warm Greeting

    Have you been thinking about the power sources and the tiles whom use blocks
    I wanted to thank you for this great read!! I definitely enjoyed every little bit of it and I have you bookmarked to check out the new stuff you post.

    Single Phase Motor