Auto AC compressor failure: The most common causes

Learn the 3 most common causes of Auto AC compressor failure

The heart of your car’s AC system is the AC compressor. It’s responsible for compressing low-pressure refrigerant gas into a high-pressure gas. However, like any mechanical part, an auto AC compressor can fail, just like your home’s AC compressor. Understanding the common causes of auto AC compressor failure can help prevent failure and keep the cold air flowing.

Compressor failure cause #1 — Lack of lubrication due to loss of refrigerant and refrigerant oil

Whether your AC compressor is a piston design, scroll, or vane type, they all require lubrication to prevent wear. However, unlike an internal combustion engine, where the bulk of the oil sits in the crankcase and is brought up into the cylinder by oil control rings, the oil in your car’s AC system is brought into the cylinder, scroll, or vanes by the refrigerant. In other words, the refrigerant circulates the AC oil through the system and into the compressor. When an AC system develops a leak and loses refrigerant, it also loses oil. From that point on, the system is not only low on refrigerant but also low on oil. Running your AC system when it’s low on refrigerant is the single best way to destroy your AC compressor.

The lack of oil causes the Teflon seals to wear, which in turn causes wear on the cylinder, scroll, and vane The wear creates fine metallic particles that accumulate throughout the system, clogging the filter in the orifice tube or the port in an expansion valve.

When the system fails, you have to replace the compressor, the expansion devices, and the condenser, along with a complete flush of the hoses and the evaporator. It’s critical to remove all the debris that spread throughout the system

Compressor failure cause #2 — air and moisture in the system degrades the oil

In addition to the loss of AC oil, a leak allows air and moisture to enter the system. Air and moisture react with the refrigerant oil, causing it to oxidize and form acids that attack the system’s metals. The now-degraded oil can’t lubricate properly, resulting in accelerated compressor wear. The wear debris, acid, moisture, and oil combine to form a slimy black coating throughout the AC system, referred to as “black death.”

Once the system is opened for repair, the slimy black film is everywhere. Fixing a black death system requires a new compressor, condenser, receiver/dryer, and a complete flush of all AC lines and the evaporator.

Compressor failure #3 — refrigerant overcharge

When the system is overcharged, the compressor has to work harder to compress the refrigerant. That wears out the compressor seals much faster and stresses the compressor crankshaft and swash plate.

Avoid all these compressor failures by fixing your AC the right way.

All of these compressor failures are avoidable by simply fixing the leak, evacuating the system, adding the right amount of oil, and then recharging by weight.

©, 2023 Rick Muscoplat