Today while driving with my sunroof open, the sun shone in on the overhead console and heated the interior temp sensor. Even though the interior temperature was not too warm (it was only 13C outside) the ACC ran the fan speed to max and began cooling the interior of the car. The ACC system varies the fan speed depending on heating/cooling needs. You should learn how to read your sensors (press REST for five seconds while engine operating) and see if you can pinpoint what is going on. Today, I checked the sensor to see what the ACC system was reading, and found the interior temp at 28C. I put my hand up, and that's when I found the heat. I closed the sliding roof, and the temp dropped to 20C and the ACC stopped freezing me.
For a list of the sensors, you'll have to do a search. I recommend "AC panel codes" or "PBU codes" and see what you get. Sensor position 01 is the interior temp and position 05 is evaporator temp sensor, which is prone to failure.
You might want to dig deeper into the AC system if it's not cooling well. I have driven my 98 C230 in 40C heat and it had no problems providing ice cold air. And I have a black MB Tex interior.
As to your tranny, the fluid temp must be 80C for the level to be properly determined. My dealer charges an hour for the change, and they use the computer to set the temp sot hey get the fluid level right. Worth it to me, and then I don't have to buy the dipstick either.
1998 C230 "Black Betty"