My 2004 Tiburon recently started having ac issues and its still pretty warm in TX. The ac will work as normal when I turn it on and its idling. The air is as cold as it should be, but when I start driving at it will stop cooling. As I slow down for a stop it will sometimes begin cooling only to stop when I get going again. I saw today that the clutch is engaging initially, but when I would rev up to around 3000 RPM the clutch would disengage completely. I wondered if the refrigerant might be low, but when it does cool, the air seems as cold as it should be. Could a compressor relay sometimes work and other times not? Thank you all for any advice.