Problems with Old Window AC Fan Motor

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  #1  
Old 07-12-10, 09:37 PM
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Problems with Old Window AC Fan Motor

I have this old high BTU AC in a fishing camp and the squirels got in the AC and chewed all the wires in two. I have the wires basically back together but now the fan motor will not start by itself. I can give it a push and everything seems ok. But it will not "kick off" by itself. I changed the capasitor out but it still will not start by itself. The capisators I have tried are 6 Mf 370 volts. They came off ACs that were working so they are good, I guess.

I checked the voltage across the capasitors and it is never 370 only 120. To get 370 out of the capasitor do I need 240 going in? I connected the fan to the compressor capasitor which is putting out 307 volts but it still will not start by itself.

Have I got something wired up wrong or what. I connected the wire to the capasitors just like the came off and even switched connections but still no go.

Any ideas?
 
  #2  
Old 07-13-10, 09:13 AM
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Is the A/C a 120-V or 240-V unit?

Failure to start is usually caused by a bad or weak capacitor. Check all the electrical connections to be sure they are tight. Your replacement cap is 6-uF - but what was the rating of the original?
 
  #3  
Old 07-13-10, 12:41 PM
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Hmmm!!!!!
I got an email where Mike Speed 30 replied to my post but I can't find it.

There it is.

Original was rated at 5 uf

Thanks Mike. Gonna get a new one and try it.
 
  #4  
Old 07-13-10, 01:20 PM
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The difference between 5- and 6-uF is negligible. But replacing the cap is worth a try.

Also: double check all your rewiring. Does the fan spin freely by hand?
 
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Old 07-13-10, 01:49 PM
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Spins very free. No problem. The wiring I think is ok, but not 100% sure.

Does the wire going to the cap supposed to have 120 volts all the time even before trying to turn on the fan. The wire from the cap has 120 volts also before trying to turn on the fan. Is this correct? It never increases when the switch to the fan is turned on.
 
  #6  
Old 07-13-10, 04:31 PM
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Is the unit 120V or 240V? Is the fan motor and compressor run at the same voltage? Check the wiring diagram.

I think there may be something wrong with the wiring.
 
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Old 07-13-10, 04:44 PM
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Originally Posted by Mike Speed 30 View Post
Is the unit 120V or 240V? Is the fan motor and compressor run at the same voltage? Check the wiring diagram.
240 Volts on both.
Only wiring diagram I see is the one on the motor. Says BK is High, BU is Medium, and R is Low. BR + W is Common to Cap and BR goes to Cap.
Can not find a diagram for the Switchs, Compressor, Etc.
 
  #8  
Old 07-13-10, 05:22 PM
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Check the voltage across the fan motor terminals with the unit running.

Did this unit work OK before your rewiring?
 

Last edited by Mike Speed 30; 07-13-10 at 06:12 PM.
  #9  
Old 07-13-10, 08:27 PM
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Originally Posted by Mike Speed 30 View Post
Check the voltage across the fan motor terminals with the unit runningOK.

Did this unit work OK before your rewiring?Yes. That is why I am thinking I have something wired wrong or something else is wrong
I typed in red the replies.

Thanks
 
 

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