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My AC Guy Says My Compressor Is Bad. How Do I Know?

Your AC guy says the compressor is bad.

That’s possible.

But a compressor is one of the most expensive parts of your air conditioner, so we’d want a little more evidence than:

“It’s not starting.”

A compressor that won’t start isn’t automatically a bad compressor.

A failed capacitor, electrical problem, low voltage, damaged wiring or another control problem can sometimes prevent a perfectly usable compressor from running.

So how do we know?

We test it.

Depending on the failure, we’d check things like:

  • Is the compressor receiving the correct voltage?
  • Is the capacitor within its rated tolerance?
  • What amperage is the compressor drawing?
  • Are the compressor windings electrically intact?
  • Is a winding shorted to ground?
  • Is the compressor on internal overload?
  • Does it start and actually pump refrigerant?

If the compressor is mechanically locked, electrically failed, grounded or otherwise proven defective?

Then your AC guy may be completely right.

Replace the compressor—or, depending on the age and condition of the system, consider replacing the equipment.

But:

“The compressor isn’t running.”

and

“The compressor is bad.”

are not the same diagnosis.

There’s testing between those two sentences.

What Should You Ask?

One simple question:

“What test showed that the compressor is bad?”

A good technician shouldn’t be offended by that.

There should be an answer.

Maybe it’s grounded.

Maybe the windings failed.

Maybe it’s locked and drawing locked-rotor current.

Maybe it’s running but no longer pumping properly.

Whatever the failure is, we should be able to explain it to you in normal English.

The Klein Answer

Could your compressor be bad? Absolutely.

Compressors fail.

But before spending thousands of dollars repairing or replacing an air conditioner, we’d want the diagnosis supported by actual testing.

Because sometimes the compressor really is dead.

And sometimes the compressor is standing there perfectly innocent while a $30 electrical component gets it convicted of murder.