Condenser Motor Stops Turning

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  #1  
Old 07-03-11, 11:07 AM
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Condenser Motor Stops Turning

Hell all. First post on here. About 4 or 5 years ago I replaced my condenser motor AND capacitor. All went well until a few weeks ago. Condenser motor stopped turning and only warm air was flowing into the house. Someone suggested a bad cap, so I replaced that. It ran for a while (not sure how long) then stopped turning again. I just replaced the cap again, in case I got a bad one. This time it ran about 15 mins, then stopped again. Each time, I noticed a slight hissing sound before the motor stopped. The motor turns freely. There doesn't seem to be any obvious binding. What else could possibly be the cause for 2 caps being blown?

On that note, is it possible for the cap's mfd rating to be TOO high? The motor's spec sheet mentions a 3MFD cap @ 370v. Both replacements were 35+5 +- 5%. Not sure what to look at next. I'm seriously trying to save some money here. Any information will be greatly appreciated.
 
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Old 07-04-11, 04:24 PM
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Are you talikning about the compressor or the fan? Either way, what's called for is systematic troubleshooting with a voltmeter and the wiring diagram. Whatever it is that stops running, does it have 240 V to the terminals when it conks out? I would replace the cap with the correct rating. Most residential A/C motors have caps with two sections, likely of different value - one for starting and one for running.
 
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Old 07-04-11, 05:55 PM
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sounds like the motor has gone bad if it runs for 15 min and then stops, like the windings are overheating. Install the correct capacitor for the fan. 5mfd is more than 10% over what is being called for (3 mfd)..........
 
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Old 07-04-11, 06:28 PM
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Thank you for the replies. The motor started fine again today. Stopped after a short while, again. There is about 230v going to the motor. The relay pulls in fine. I guess it could be the motor. The technical drawing for the motor mentions 3mfd. Does that make it a start cap or a run cap? The last 2 caps that I bought had 2 values listed (35 + 5). Should I get one that reads only 3MFD (no + added)? Does it matter if the cap has 2 or 3 terminals? The original drawing on the condenser's panel shows a 3 terminal cap. Should I just go with a cap that matches the new motor, even if it calls for a 2 terminal cap? Thanks again in advance.
 
  #5  
Old 07-04-11, 07:23 PM
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Use a cap that is for the new motor. Take your old one with you to pick up the new motor and cap. It is a run cap.
 
 

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