Alright, here's the deal.

My BMW has an intermittent leak. Sometimes I can go months without having to charge the A/C, and other times, it has to be done daily. So something tells me its a valve or something.

Yesterday I got in the car after it had been sitting 4 days (been driving the Corvette everyday), and I figured the A/C would be non-existant. Bam! It was there and it was cold.

The fact that sometimes it leaks and sometimes it doesn't, really throws me off. Anybody have any ideas?

How have you been re filling it? You or the shop?
Sometimes the shrader valves will cause you an intermittent leak.

I've been refilling it. I'm gonna give the shrader valve a good once over.

We used to put dye in the system but you might be able to use a soap solution. If you are lucky and it is the valve, and you happen to use the solution when it's leaking it will make bubbles.

As the proud new owner of an 8 year old driven-hard-and-put-up-wet Grand Prix, I was just thinking today - why wouldn't it be a good idea to just put the dye in every car? Seems like it would save a trip later on, since when problems occur you usually have to make one trip just to be told "we'll put the dye in and then come back when it acts up again."

This Pontiac's a/c is great - 40F at the center vent on recirc after it's been running for a few minutes, and no compressor noise. But we intend to put a lot of miles on it before we're done with it.