Originally Posted By: 901Memphis
I'd use the AC once in awhile to circulate the oil in athe system.
That's obsolete advice.
Automotive A/C system switched to barrier hoses and HNBR seals with the conversion to R134 about a quarter century ago. The switch to carbon face seals on the compressor shaft occurred well before then.
Older systems were far less sealed. They relied on a film of lubricating oil, almost always mineral oil with additives that made it sticky. It was primarily the oil film, not the rubber of the hose, that kept the refrigerant from escaping. When the oil film got thin, diffusion increased.
I'd use the AC once in awhile to circulate the oil in athe system.
That's obsolete advice.
Automotive A/C system switched to barrier hoses and HNBR seals with the conversion to R134 about a quarter century ago. The switch to carbon face seals on the compressor shaft occurred well before then.
Older systems were far less sealed. They relied on a film of lubricating oil, almost always mineral oil with additives that made it sticky. It was primarily the oil film, not the rubber of the hose, that kept the refrigerant from escaping. When the oil film got thin, diffusion increased.