Published on Nov 20, 2024|Updated on Sep 5, 2025|By: Gary McCreadie

How To Avoid Premature Compressor Failure

How To Avoid Pre-Mature Compressor Failure
Key Takeaways
  • Common Failures: Compressor failures include shorted windings, shorts to ground, and seizure from lack of oil – all preventable with proper installation and maintenance
  • Installation Best Practices: Nitrogen brazing, proper pipe preparation, deep vacuum with decay testing, and correct refrigerant charging are critical for compressor longevity
  • Testing Methods: Use a multimeter to check for shorts to ground and verify winding resistance against manufacturer specifications (available in apps like Copeland Mobile)
  • Maintenance Prevention: Regular maintenance detecting dirty coils, worn contactors, failing capacitors, and airflow issues prevents premature compressor failure

In my almost 30 years of performing HVAC and refrigeration service, I’ve encountered many premature compressor failures. These failures weren’t all the same. They were a scattered mess of destruction.

Shorted windings, shorts to ground, leaking electrical terminals, failed internal parts, seized from lack of oil etc, can all happen… But they all can be avoided.

Let’s look at a few common failures.

Compressor Shorted To Ground

This type of premature compressor failure happens when a portion of the compressor windings shift loose from their tight bundle and come into contact with the body of the compressor. In most cases this is known as a dead short and will instantly pop a fuse or open a breaker.

This can be checked with a multimeter set to ohms. Place one meter lead on a compressor terminal pin and the other lead on a good ground reference. Ensure to repeat the process for all compressor pins. There should be no measurable resistance from each pin to ground. If there is, you have a winding short to ground.

Compressor Windings Are Shorted Or Open Windings

Compressor windings in general, have published resistance readings by the manufacturer. For example, the Copeland Mobile app has their resistance readings published for each compressor model. This can be easily looked up by either scanning the compressor bar code or by manually entering the model number.

Shorted windings and shorted to ground are not the same thing. A shorted compressor winding only can’t be referenced to ground. If a winding has a published reading of 5 ohms for example but reads 1 ohm with a multimeter, the winding is considered shorted.

If the winding reads 100 ohms when it’s supposed to read 5 ohms, we can consider that winding to be open or partially open. If the winding were to read OL (open line), the winding is fully open.

To check this, set your meter to ohms and check across each set of pins and then check it against the published winding resistance readings.

Seized Compressor

A compressor is seized when its internal parts aren’t lubricated enough with oil and metal on metal friction (galling) begins to happen. A lack of oil return or copper plating can cause this. Copper plating is the build up of copper alloys on compressor parts, which puts the tolerances out by adding another layer of metal to moving parts that it wasn’t designed for. Copper plating is caused by acid in a system (which is often a side-effect of moisture).

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Best Practices During Installation To Avoid Premature Compressor Failure

Pipe Prep

After a piece of pipe is cut, there is a lip created on the inside of the pipe. This lip can restrict oil flow on its way back to the compressor. The lip can also create refrigerant turbulence at the joints and can cause leaks down the road.

The lip should be reamed, ensuring the pipe is pointed downward so any copper filings fall out during the process.

Cleaning the pipe with a Scotch-Brite pad or similar will ensure the pipe is clean and that silfos will penetrate well.

If pressing pipe, the process is very similar. Here’s a video on how to press properly using Rapid Locking System.

Nitrogen Braze

Brazing is done at a high temperature, approximately 1300°F. During this process the build up of copper oxide is present. Copper oxide on the inside of a pipe will be swept away by POE oil, acting like a detergent and scrubbing the pipe walls.

Copper oxide can restrict metering devices, this can lead to less suction gas moving back toward the compressor, less suction gas, more heat and less lubricant. Sounds destructive to me, how about you?

If you wanted to avoid brazing, there are alternatives which can be used in the right situations.

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Gary McCreadie

Gary McCreadie is an HVAC tech, the creator of hvacknowitall.com, the HVAC Know It All Podcast, and owner of McCreadie HVAC & Refrigeration Services

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