Automotive Air Conditioning Information Forum

Warning: don't ask me the time unless you want to know how to make a watch.
Scroll compressors FYI:
The moving/orbiting scroll is anodized aluminum and the fixed scroll is softer and not anodized so that it can wear in to conform to the hardened moving scroll. This process during early operation results in;
1) Tiny gray particles in the oil which turn the oil gray.
2) Gradually improving volumetric efficiency by 2 or 3% as blow by is between scrolls is reduced (and increased cooling performance).
The thermal protection switch TPS, is in the clutch electrical circuit and prevents compressor operation with a wrong refrigerant charge or poor condensing.
Installation of the thermal switch is critical to provide thermal silicone completely on the contact surface and not dent the bottom case to distort the internal bi metal disc.
Rebuilders and knock offs often do not do this properly.
E,G, if silicone has gaps, water will get between the TPS and the compressor and freeze and dent the TPS can.
Also rebuilders need to scrape out 100% of the old harden silicon before reassembly to prevent TPS denting.
Hope this helps y'all
hotrodac

ice-n-tropics wrote: ↑Sat Jun 29, 2024 8:39 am The moving/orbiting scroll is anodized aluminum and the fixed scroll is softer and not anodized so that it can wear in to conform to the hardened moving scroll. This process during early operation results in;
1) Tiny gray particles in the oil which turn the oil gray.
2) Gradually improving volumetric efficiency by 2 or 3% as blow by is between scrolls is reduced (and increased cooling performance).

My understanding is that some scroll compressors have slight clearance (~0.002") between the fixed and orbiting scrolls so that, in theory, they never touch and "color" the oil. I'm not clear whether this applies to MVAC scroll compressors, though.