Capacitor Failure?
How Does It Effect Refrigeration Equipment?

A defective capacitor affects the refrigeration equipment in different ways.

Single phase PSC motors usually display two signs of trouble.

Anytime I see a PSC motor start slowly and labor to reach it's normal rpm, I immediately suspect the run cap.

Usually the motor never reaches full rpm before it stops.

That brings me to the second sign, overheating.

What causes the motor to stop?

If you touch the motor it will be extremely hot.

Most fan motors have internal winding thermostats. They protect the motor by opening under extreme temperatures, stopping the motor.

Want another sign?

Believe it or not, sometimes I can actually smell an overheating motor.

By standing in the discharge air of a hot motor, a burning smell is noticeable.

It's not an electrical burning smell but closer to a paint burning smell.

So there you have it. If you find a motor that runs slower than normal or stops, is hot to the touch, and smells like paint burning, check the run cap.

As for single phase compressors, bad run and/or start caps almost always result in a stalled unit.

The compressor refuses to start or run.

The potential relay, start cap, and run cap must all be working correctly. A malfunction of any one usually causes the failure.

They are mutually dependent upon each other.

Sometimes you can replace one of the three. But over the years, I have always had less call backs by replacing all three.


I think a failure of one, damages the other two. So why take a chance.

It is amazing how much information about capacitors can be easily gathered before you even grab a diagnostic meter.

Simply look, touch, and even smell, you may be well on you way toward getting that refrigeration system up and running!

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