Need help troubleshooting problem with coleman central air unit, already replaced fan, still not comming on.?

Question

A few days ago i noticed the unit outside was on for quite a long time, shortly thereafter, i noticed the fan wasn't turning and it was making a loud humming and i immediately turned it off. I waited about an hour for it to cool and tried it again and it only hummed so i turned it off again. Based similar problems folks were having i thought it would be the motor so i replaced the motor tday, it is also recommended that the capacitor be changed however the new capacitor is not a dual capacitor so i wasn't sure how to rewire it using a single capacitor so i just put the old back in. I could just probably get two of the same capacitor and just wire them seperately using the common? Any way i turned the unit back on and it does the same thing. Looking closer, i see the contactor engaging however the compressor seems to engage then stops, engage then stops. I'm at a lost, is the old capacitor bad, should i get a second new one and wire them seperately? Thanks

Answer 1

I assume this is a 220volt system, so check and make sure both legs of the cicuit are live.  You just may have a partial breaker or fuse problem and only getting 110 volts, which will cause the humming sound.  

Also if the freon level has dropped, the unit will not start, but the humming sound leads me to believe the unit isi not getting the full power needed to operate.

Answer 2

no that your old one to the store and get the right capacitor for that unint. that get the rpm for the motor to started it.

Answer 3

A fan motor is just bearings and 2 windings;A start winding and a run winding(there is also a centrifugal cut out switch inside but people seldom mess with those).So if the bearings are not stuck(shaft can be turned by finger) and the thing isn't on fire(due to shorted windings) ITS THE CAPACITOR!!! (which is used in series with the start winding and the centrifugal cut out switch,)I am sorry you went and bought a motor(can you get your money back??) But all you needed was a capacitor.Well remember this for the future