A/C Help. May be Condenser or fan motor


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Old 09-27-08, 05:08 PM
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A/C Help. May be Condenser or fan motor

I have a problem with my central a/c and it may be with the condenser unit. Incidentally, the evaprator uint is in th attic. When I turn it on air comes out of the vents but it is not cold. I checked the outside unit and noticed that the fan blades inside are not turning. There is a also Humming noise. I inserted a long stem screw driver and was able to turn the fan blades freely. There is an electrical box near the unit and when I truned it OFF, the humming noise went away confirming that the unit the getting electricity. What could be the problem here? I have a basic meter (Analog and also DMM), but don't know what to look for and how to test it. I can learn. Any ideas?
 
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Old 09-27-08, 06:31 PM
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Leave it off overnight to let it cool. Then try again tomorrow. Take note of the condensor fan, whether it spins. If it doesn't, the compressor will go out on the internal protector or high pressure switch. If condensor fan inop. then it's either a bad motor or capacitor, assuming the contactor and wiring is OK.
 
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Old 09-28-08, 08:15 AM
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if the compressor is runnnning without the condenser fan it is either the CAP or the MOTOR itself.there is one contactor that when the stat calls they both start so you have 208V if the compressor is running but the cond fan isn't.the motor is 115V if you say it is free spinning when you spin it its not the bearings.you need to RING the condenser motor windings out.shut the condenser power off and access the contactor area...pull the condenser wires off the contactor and the CAP write down all terminals where the wires came from(total wires in your hand at least 3 maybe 5.put your meter to audible and hit 2 wires at a time should here the beeping showing the winding is solid(no sound the wire/winding is open)the motor needs change out.if you RING all the wires from the motor then its the CAP change it out local Grainger welcomes DIYs over the counter $5.check the wires(from the condenser motor) to the motor casing just to make sure they aren't grounded...if they were,the fuse would be blowing on contactor closure.
 
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Old 09-28-08, 07:22 PM
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Air Conditioning Problems

It is possible that you have a bad capacitor but if that was all the fan should have taken off after you spun it I think it is more likely that the line voltage is not getting to your condensor and the humming you are hearing is just the contactor. Check your breaker or fuses to the outdoor unit first, then use your meter and check for line voltage at the bottom of the contactor or wherever the incoming power terminates.
 
 

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