MOTOR has talked about compressor failures for years, and this year’s MACS convention seminars on compressors produced new evidence of some of the same problems. And whenever we think we’ve identified all the issues, along comes new information. The compressor seminars did make some points well worth mentioning:
At the top of the list: A “just-low” refrigerant charge (typically a 10% to 20% undercharge) significantly re-duces oil flow, according to Four Seasons’ Jim Johnson. He gave this example for 88°F ambient: The a/c duct temperature rose just 3° (from 46° to 49°F), hardly enough for a customer complaint. Yet so much oil was trapped in the evaporator under low-refrigerant conditions that oil circulation dropped from about 10% to 25% by weight to just 2% to 4%. That’s a prescription for increased compressor wear and therefore short compressor life.