Outside unit fan not spinning, humming.

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  #1  
Old 06-10-15, 04:39 PM
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Outside unit fan not spinning, humming.

I noticed my AC was no longer cold, even though it was blowing through the vents. I visited the outside unit and it was humming, lightly, but the fan was not running. Without turning the AC off inside the house, I pulled the fuse on the electrical box behind the AC unit. There was no change and the hum did not stop. Next I turned off the breaker but again, the hum did not stop. Finally I turned off the AC unit in the house via the control panel and the hum stopped.

I turned the breaker back on, plugged back in the fuse, and turned the AC on via the panel. It still hummed the same. I attempted to rotate the fan to see if I could get it to start, but it did not. Also, I did notice the fan had some resistance and didnít exactly spin freely.

After a few moments it sounded like the compressor kicked on. The unit got very loud. The entire AC unit itself began getting hot so I turned it off via the inside control panel.

Iíve had the unit stop working in the past but it was covered under our home warranty. I seem to recall the unit needing to be recharged, but thatís all I remember.

Any advice?

Make: Carrier
Model: 38YKC024300

Thank you!
 
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Old 06-10-15, 07:04 PM
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Welcome to the forums.

That hum you are hearing is the contactor. The thermostat sends out 24vac to activate it and it doesn't matter if the outside unit has power or not.... the contactor closes.

Your problem is the condenser fan. It could require a replacement capacitor or a new fan motor.
Is this something you are trying to fix yourself ?
 
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Old 06-10-15, 07:08 PM
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Sounds like a fan motor issue, but without the fuse, the only power you have is the 24V at the contactor. wonder where is the humming come from. I'll check and may be replace the contactor first, if that does not fix the problem, replace capacitor, do the fan motor last. (contactor and capacitor are cheap, so do them first)
 
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Old 06-10-15, 07:24 PM
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clocert...read the problem again. The OP stated the compressor was coming on.
 
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Old 06-10-15, 08:39 PM
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I know, but the humming was come from the contactor. The contactor should not make humming sound, and it is so cheap ($10), I'll replace it anyway.
 
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Old 06-10-15, 08:45 PM
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Many contactors hum. You normally don't hear it because the unit starts running.
 
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Old 06-10-15, 08:49 PM
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I always test them in the shop without fan or compressor, they don't hum. all you hear is a click. If they hum, I throw it away.
 
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Old 06-10-15, 09:55 PM
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I'd open the panel and visually inspect for swollen capacitors and burned wire connections.

The problem is probably the capacitor. The motor is less likely but a possibility.

Since you have that Ykc in the model number it sounds like your have a 10 seer heat pump. Heat pumps have a defrost timer that also interrupts power to the fan motor.
 
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Old 06-11-15, 07:13 AM
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Thank you for all the responses.

That hum you are hearing is the contactor. The thermostat sends out 24vac to activate it and it doesn't matter if the outside unit has power or not.... the contactor closes.
This is what was worrying me. I didn't want to start taking off panels near the electrical components without knowing the unit was off. I'll disconnect everything and turn off the thermostat before inspecting further.
 
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Old 06-11-15, 04:24 PM
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RESOLVED

I was able to lubricate the fan shaft and it fired right up.
 
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Old 06-11-15, 08:58 PM
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Keep an eye on it as external lubrication is usually only a temporary remedy.
 
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Old 06-11-15, 09:10 PM
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UPDATE

Turns out the lube that fixed the fan may not have been the actual fix. After putting everything back together it stopped again. I went out and found some of the wires were hitting the fan blades, causing a short. This may have been preexisting, and moving the fan may have cause the short to temporarily go away. Anyways I rewired it and ensured they were no longer in the way of the fan blades. I'll keep en eye on it.

Thank you for all your help!
 
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