Now this is not a diagnosis. But, have you had the vaccum actuators checked to see if they are holding? (these control the where the air directs itself into the cabin and the hot air/outside air mixture)

These are a common failure on the Benz - especially these models from that era. Maybe the A/C is mixing with the outside air too much and therefore it is not all that cold. I had that problem on my benz. Also check the Klima Relay. On mine when extremely hot out, it would have a false connection within (solders) that caused that the A/C would not function to par.

Also, are you sure the system is not leaking or leaked freon therefore you feel it more on hot days - is it fully charged?

Furthermore, I recommend that you do a search and read up on the subject within the forum. Lots of info about the A/C systems and the actuators and the Klima relay and even the push button control that can be part of your problem.

If you not upto speed on all of this - either study and read the posts here or at least take to an indy and pay for an hours time and get a diagnostic. For them to check the actuators is not hard, the central vacuum distribution thing-a-ma-jig is located behind the glove box.

Iggy

__________________
Insanity: doing the same thing over and over again and expecting different results.

2006 - Suzuki Gran Vitara (2.0 L fully equipped) Like this car so far except for trying to put on the seatbelt.
1988 - 190e - 2.3L - 172K miles (It now belongs to the exwife)
1999 - Chevy Blazer LS Fully Equiped - killed it June 2006
2001 - Honda Civic EX - 68K miles (sold June 2004)
1963 - 220S - Dual Carb 6 cyl. (sold)
1994 - Yamaha WaveRaider (fun to ride)