I had a "specialist" rebuilt my A/C, we replaced evaporator, put a new expansion valve, and surely put a lot of money on the a/c of my 240D '81. This is about the third time I do this on the last 8 years. Can anyone tell me what are the correct amount of pressure in the a/c system? and why this cooling system has always been very poor in my car. I live in a tropical place and temperature normally hovers around 90 F. any comments will be appreciatted.