Next size up for AC capacitor that keeps blowing?

Problems related to residential installations.

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Next size up for AC capacitor that keeps blowing?

Post by robbwilson » Thu Sep 15, 2011 11:51 am

The run capacitor for my AC system keeps blowing, sometimes in less than 3 days from the time I replace it on the 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 shore) has upped the resistance in the motor and it requires more juice to get it to start. Once running, everything is fine.

The capacitor - AmRad P/- VA2000/37-156K RHEEM P/- 43-20847-41 --------- 15.0 MFD 370 VAC Oval Run Capacitor

- 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 replacement capacitors from Grainger. Is their quality OK, or should I go somewhere else?


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- Next size up for AC capacitor that keeps blowing?

Post by heatseeker » Fri Sep 16, 2011 8:50 am

a ten year old rheem with a 15 mfd capacitor does not sound right at all. should be more like 5 mfd you need to research the blower motor specs and get the right capacitor. but its probably too late sounds as if your motor is bad anyways.

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- Next size up for AC capacitor that keeps blowing?

Post by Freon » Sun Sep 18, 2011 8:44 am

Do not change the value of the capacitor you are replacing. PSC motors are designed for a specific microfarad capacitor to generate the correct horsepower and rpm. I would double-check exactly what values are called for, both the compressor and fan, in the condenser unit. It is possible there is another cause for the rapid capacitor failure. You can increase th rated operating voltage to 440 but I doubt that will help.

You really need to measure the current draw for both the fan and compressor. I assume it's a dual capacitor so it would be nice to know which capacitor is failing, compressor or fan. If it's the compressor side, you may try a hard start kit to see if that helps.

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