Can I just bump up the Micro Farads?

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Old 09-15-11, 11:04 AM
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Can I just bump up the Micro Farads?

Hi,
The run capacitor for my AC system keeps blowing, sometimes in less than 3 days from the time I replace it on the inside air handler of my Rheem system. The compressor and air handler are both 10 years old, so I'm thinking wear and tear on the motor windings and exposure to salt air (unit is near seashore) has upped the resistance in the motor and it requires more juice to get it to start. Once running, everything is fine for a day or two, until the capacitor blows again (evidenced by a swollen top on the capacitor). I live in Bahamas, so clean AC and reliable diagnosticians are not a given. And power outages and spikes occur. But I recently installed a very expensive surge protector on my panel to take care of surges and spikes, so I don't think that is the problem. Though voltage drops might be? The second (smaller) unit in Zone 2 of the house, which also needed a new capacitor this year, runs consistently with the replacement capacitor.

The capacitor that was originally on the unit, and which I have now replaced 4 times, is a 15.0 MFD 370 VAC Oval Run Capacitor: RHEEM P/N: 43-20847-41

Question: Is the solution here to move to the next higher microfarad level? Say going from 15.0 to 17.5 or 20.0?

I"ve been buying the capacitors from Grainger. Is their quality OK, or should I go somewhere else? I'd love to buy American if someone has a source.

I'd appreciate any advice/guidance.

Thanks,
Robert
 
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Old 09-15-11, 02:31 PM
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Sounds like you need a new motor! Stop messing with the capacitors and put a new motor and cap in.
 
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Old 09-15-11, 11:12 PM
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Thanks! Any guidance on how I should test to determine if the bad motor is the fan motor in the air handler or the fan motor in the outside compressor?
 
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Old 09-17-11, 06:32 AM
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The compressor wil not have a 15mfd cap unless it is a small window unit.

Read the 3 cap sizes and replace the motor that is connected to the 15mfd cap.

Common sizes for compressors run from 35 to 80 mfd.
Common sizes for condenser fan motors run from 3 to 10mfd.
Common sizes for indoor fan motors run from 7.5 to 15mfd.
 
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Old 09-17-11, 06:55 AM
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Originally Posted by robbwilson View Post
Thanks! Any guidance on how I should test to determine if the bad motor is the fan motor in the air handler or the fan motor in the outside compressor?
Which capacitor is blowing, that would be the one.
 
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