See What’s Inside a Scroll Compressor

This scroll compressor received the notorious “not pumping” diagnosis. When we opened the compressor, we saw that there was grit all over the place. Removing the top scroll caused little pieces of metal to fall everywhere, but the scroll itself appeared to be in decent condition. The bottom scroll also appeared to be in fair condition, but there was some mechanical wear on the copper plating. There was major scoring on some of the unidentified parts that had come off.

It appeared as though the compressor had a winding burnout, as there appeared to be acidic oil on the inside. Further investigation of the call notes indicated that an acid test was performed and came back positive, confirming our suspicion of burnout.

The pieces throughout the system likely came from the windings and some other parts of the system, which probably caused the motor to short out. So, there was a combination of burnout and mechanical failure.

The terminals on a scroll compressor work the same way as they do in a reciprocating compressor, but these scroll compressor terminals were highly susceptible to melting given the type of failure we saw.

Eventually, we’d like to cut the compressor even further to look at a cross-section of it. However, since we took the scrolls out, you can see how the top scroll has an orbiting action that results in oscillation between the scrolls, which is how the compression happens. The gas goes in through a large port on the side and gets trapped between the two scrolls, becoming smaller and smaller in volume as the top scroll moves. Then, the gas gets discharged through the center.