A reader asks:

My car needs a new AC compressor, but the repair shop says they can’t warranty the new compressor unless I buy a new AC condenser to go with it. Why? Is this a trick to get me to spend more money?

It’s probably not a trick, only it wouldn’t hurt to get a second opinion. Compressors and condensers are often replaced simultaneously, mostly because compressor failures leave behind debris that the condenser collects. If this debris isn’t 100% removed, it will cause the new compressor to fail as well.

Why AC Compressors Fail

Generally speaking, AC compressors only fail for a handful of reasons:

  1. The AC system loses refrigerant, increasing compressor wear and tear to the point where some part of the compressor fails. Refrigerant carries the lubricant the compressor needs to function, so a refrigerant leak increases friction.
  2. A clogged or damaged condenser can also cause compressor failure, as a poorly functioning condenser won’t remove enough heat from the refrigerant. This can sometimes mean the refrigerant remains in a liquid state when it’s pumped to the compressor, and that’s bad.
  3. A clogged cabin air filter can cause a similar problem as  clogged or damaged condenser, as it can reduce the efficiency of the AC system to a point where the compressor is pumping liquid refrigerant.

As you can see, condenser problems and compressor failures are often related. Thus, it might be a good idea to replace a condenser when your compressor fails.

What’s more, when a compressor fails, there is a tremendous amount of debris that is suddenly injected into the AC system. This debris comes from the failed compressor, and it’s almost impossible to remove this debris completely from the condenser.

If the original condenser isn’t replaced, the risk is that a small piece of debris that’s left behind in the original condenser will cause the compressor to fail again. Therefore, many replacement AC compressor warranties require replacement of the condenser…which is probably why your mechanic is telling you to replace both parts at the same time.

Bottom Line: If your mechanic is telling you to replace your compressor and condenser at the same time, he or she is probably correct.

To learn more about why AC compressors fail, check out AGCO automotive’s extensive write-up here.

About The Author