For what it's worth, I have a 420 SEL where ac seemed to work fine but the air getting warmer and warmer. I've had the car for 2 months, and noticed that there was oil on the lines leading from the condensor (the grill like component attached to the front of the radiator). Took it a shop, they vaccumed the lines and refilled with oxegen then checked for leaks. Sure enough, the rubber line leading from the condensor to the dryer had a leak. Line cost $27, will cost about $175 to have it installed then recharged with freon. In my case, as the freon leaked out the system got warmer. Maybe your's leaked overnite. Just a thought. Good luck!