Ac outside unit, the fan shuts off about 15 min after starting why?

Question

I check the capacitor with a meter and it was good. The disconnected wasnt tripped outside. The compressor was still running so im still getting power outside. Contactor was passing proper voltage through it and also giving the 24 volts on the coil. Did notice when fan shuts off, the motor is really hot to the touch. I ohm out the motor and theres no open windings so it looked good. Had a amp meter and checked amp draw. The FLA for the motor is 1.3 when it shut off its 1.8. So thats probably why its hot,running too much amps through it. What would cause all this, someone please help!!

Answer 1

Sounds real simple to me. If you have power to the motor and it stops running, it is bad.

Possible it is dirty and overheating. You might try hitting the vents on it with compressed air if it is not a sealed motor.

But more likely you have a bad winding that opens or shorts some when hot. Or could be the start winding is not opening up after it starts and it is drawing too much power.

Good Luck.

Answer 2

Fan motor is overheating and tripping it's internal thermal overload.  With power off, grab the shaft at the blade hub, and see if you get any lateral play.  If you do get even a tiny bit, the bearings are worn, and causing it to overheat.  Typically, when a motor with bad bearings first starts, it'll sound funny, kind of like a heavy humming sound that clears up once it comes up to speed.    Sounds like you're due for a new motor.  If you opt to do it yourself, they're not very expensive, and it's a pretty easy job.  Just make sure you have the same horsepower, voltage and rotation,...be sure to match the capacitor to the new motor.   Good luck.

20+ yrs HVAC Tech

Answer 3

Sounds like the motor is going out on internal overload. Is the condeser clean?, has the fan been replaced or the has the fan slipped on the shaft? If t was mine I would probably replace the motor if there was no obvious reason external the motor.