Checking blower motor

[tf1182]

I'm new to this forum, and relatively new to hvac within the last 4 months or so. I've taken a fundamentals hvac class to get my EPA and learned the basics in residential HVAC systems and operations.

I'm trying to learn as much as I can to become a service technician for my company. I currently work with others but would like to impress my boss and learn as much as I can to be able to go out on my own as my experience grows.

I was wondering if you guys could tell me the sequence on checking whether or not a blower motor is bad or if its just a capacitor problem. This maybe an easy question but I'd like to know for sure so some day I can diagnose quickly whether its a capacitor problem, a motor problem or a board problem, ect.

Share your wisdom please!

[54regcab]

A quick way to check is manually start the blower wheel then apply power. You may need to jumper R to G then plug the unit it while the blower is still spinning from your manual start. If the motor runs you have a bad cap. Be VERY careful using this method, done wrong it can take fingers off !!!

[Brad1980]

If the motor should be running and its not, use a multi meter to see if you have 24V between G & C. If you have 24V make sure you are getting the proper voltage to the motor (120V, 240V depending on what your working on) To do this check between the fan speed wire and the common wire that go to the motor. If you have the proper voltage. Turn off power to the unit and check the capacitor. If the capacitor is good then the motor is bad. (this is a very basic discription) I would recommend to someone new to get comfortable using your meter. It will be your best friend. Hope this helps.

[hewitt]

Check microfarads of capacitor. Also u can check all windings using a ohmmeter

[tf1182]

Thanks guys, I appreciate it!

[BPToilman]

Just ran into this today. Unit Was buzzing When i got there. Compressor or motor? Fan spun easily. I threw a hard start on to see if I could get the motor to start. Wouldn't go but pulled the compressor in. Got the capacitor tester and of course the capacitor was no good. Those testers help if your not sure. Very simple test.

[jjmarquez84]

Yeah I would 24v first and then check your main voltge at the contactor. If everything reads out fine then check your cap. These are a few steps that I use.