This is a central air unit for an apartment. When the a/c is turned on, the blower motor works but the fan motor outside doesn't work. The motor outside makes a humming noise, but doesn't turn. I removed the motor and capacitor and took them to an electric repair shop. The capacitor tested good, so did the motor. Then they put the motor in a vice with the capacitor and hooked it up to 220. The motor ran fine. What should I be looking for in the air conditioning unit?
It sounds like one leg of your 220v in the condenser(outside unit) is not getting power to the fan. Grab a volt meter and check voltages at the contactor inside the condenser.One side is 24 volts from the thermosatat and the other side is 220 volts for the compresser and fan. Be careful! You did not mention if your compresser kicks in even briefly. Check all connection from the inside circuit breaker out to the condenser. It could be a loose connection, a bad breaker, a tripped breaker, or a bad contactor. If you are not familar or comfortable working with electricity, have someone who is do the testing. Turn off power before checking connections for looseness.
If the motor and capacitor tested fine, check the contactor that supplies power to the fan motor. Use a voltmeter to verify that both legs of the circuit are making contact. (The contactor is the relay that supplies power to the fan motor). They cost around $23 or less at Grainger. Also put the fan back into your unit and try it again. We used to have a fan motor that would stick while not being run in the winter, then when we needed it in the summer, I would have to go out the first day and give it a push to break the stuck position. Then it would work all summer. Now that you got it broke loose, it may work for you now. ?? Try it.
Check contactor in the outdoor unit for voltage and loose wire connections. Also, for pitted and burnt contacts, with the POWER OFF at the disconnect.
