I finaly turned on the AC this week (I live in Maine) and we have no cold air.

1. Check Fuses and relay, All good
2. Check compressor, I can hear it running but the engine doesn't rev up
3. Checked and filled AC

I'm still getting warm air and now I have a hissing sound from under the driver's side dash when the AC is turned on. The sound stops if the AC is shut off.

Any thoughts?

 

My dash also has been making a hissing sound from under the driver's dash with the AC on...although mine is still blowing cold air. The dealer told me that it was 'normal,' saying that the pipe works for the AC are quite narrow for a small car, which causes the hissing. I feel that it is a hissing time bomb (to AC failure...not to a Mini Kaboom!).

Sorry I don't have any really useful info about your dead AC, though. I hope it's a simple fix.

 

Hopefully reviving this. Has anyone else had this problem, know the cause and had it fixed? This issue (same symptoms as the original post) just started on my 2010 MCS. The low side pressure is about 35psi while running the ac in this condition.

 

Apparently there's a tiny leak somewhere in my AC. Over 5 years the refrigerant leaked out but the system still holds pressure. Had it evacuated, dyed, topped off and it runs fine. They couldn't find the leak visually, nor with a sniffer but the dye will reveal it someday.