Legacy A/C Compressor

If you encounter a customer complaint of A/C blowing warm air and after basic diagnostics (gauge readings, etc.), the compressor is found to be seized or not pumping, examine the oil from the failed compressor for metal particles. If you find metal particles, make sure the entire system is flushed using a solvent such as "Brake Clean"* (examples: Permatex; CRC; Snap; all offer a brake parts cleaner that dries with no residue) and shop compressed air. Just changing a receiver-dryer may not be sufficient in stopping the particles from clogging the expansion valve and possibly the bellows valve in the compressor. Compressed air can contain moisture, so allow the system to be evacuated longer than the 30 minutes which is for a new system unopened to the outside atmosphere.

*NOTE:
Because of changing laws concerning refrigerant release into the atmosphere, air conditioning manufacturers are recommending alternative system flushing procedures to comply with the Montreal protocol.