The tech that looked at my AC said that the OEM compressors can limp for years making the whirring/rattling sound. My system still blows ice cold. I'd like to stay with the Freon system ( hot summers in Oklahoma) so I'll probably just swap in another low mile OEM compressor. Any chance the compressor could just be low on oil? All these OEM compressors are getting old...so just putting in a salvage unit may lead to problems. Who has the best rebuilt OEM units ? Can anyone vouch for rebuilt units ?