Hmmm, when you are low on refrigerant, the system *should* still cool, but not as much. If it suddenly went warm, I was suspect the problem is elsewhere. You should try and get some codes out of the A/C system.

1. Put the key into the ON position (position 2), but make sure the car is off.

2. Put the climate control into AUTO and LO.

3. Press and hold REST and DEFROST (front/windshield defrost) at the same time until you read dIA on the climate control screen.

4. Using the AUTO button, scroll through the codes, and record them. Report the codes back to me and I will tell you what they mean.

GOOD LUCK!

__________________
2006 E350 w/ 155k miles (Daily Driver)

Previous:
1993 300E 3.2L Sedan w/ close to about 300k miles
2003 E500 Brilliant Silver (Had 217k miles when totalled!)
1989 300E with 289,000 miles (had for <1 yr while in HI)
03 CLK 500 cabrio (Mom's)
2006 C230k (Dad's)
1999 S420 (Mom's/Dad's)
2000 C230k Sport sedans
2001 CLK320 Cabrio (Mom's)
1995 C280 My First Mercedes-Benz... (155k miles. EXCEPTIONAL AUTOMOBILE. Was Very hard to let go of!)