Take the 2-minute tour ×
Home Improvement Stack Exchange is a question and answer site for contractors and serious DIYers. It's 100% free, no registration required.

Last year my home's central air condenser fan motor stopped working. When I noticed the house wasn't cooling down I went outside to investigate and found there was a humming sound coming from the unit, but the fan wasn't turning.

After researching the problem online, I found the capacitor may be bad and causing the problem. The capacitor wasn't blown, but I replaced it anyways. The problem still existed; Fan won't spin and a humming sound is coming from the unit.

So, I inferred the motor must be bad. Yesterday I unbolted the fan from the unit to try and spin the blades by hand. To my surprise, it spun. It spun 3 to 5 rotations with a medium amount of force (the same force it would take to bounce a basketball 8 feet in the air). I expected the motor to be stuck and not spin at all, so now I'm second guessing myself.

My question is: How "freely" should it spin? I've read in numerous places that the blade should spin "freely", but I'm not sure what that means. Should it spin around 50 times with a medium amount of force? If I was holding it up in the air, should a 15mph breeze spin the blades like a pinwheel? Or is the 3-5 rotations freely?

share|improve this question
1  
Is that an official NBA basketball filled to regulation PSI? –  Tester101 Apr 3 '12 at 16:23
    
Any update on if a new motor fixed the problem? I'm in a similar situation and am curious as to your results. Also, where did you get the replacement motor from? –  mikeazo Aug 14 '13 at 19:22
    
mikeazo, it was the fan motor and it's been running fine ever since. I purchased the motor from Grainger. Make sure you get a capacitor (or capacitors) to match the new motor. –  anthony Aug 24 '13 at 14:52
add comment

1 Answer

up vote 2 down vote accepted

If you replaced the start capacitor, and you are getting proper voltage to the fan motor than the only thing left is to replace the fan motor. If the fan turns at all without forcing, it should spin when powered up. If the fan turns freely or not is not a definitive indication that is good or bad.

share|improve this answer
    
This. A wire in the armature could have melted, introducing a short or discontinuity that prevents the current in the wire from having the proper electromagnetic pull to move the armature. The commutator could have gone bad (again shorting or opening the circuit). There are several ways an electric motor can fail that leave it spinning relatively freely, and in fact I say it's generally a toss-up between overheating causing the bearings to burn out or the armature to warp (seizing the motor) and these other failures. –  KeithS Apr 3 '12 at 16:32
    
Thanks guys, I'll order a new motor for the unit. –  anthony Apr 4 '12 at 14:33
add comment

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.