I have a 2000 280C. I had low freon pressure of 25psi and added a canister to bring it up to 40psi. The AC worked great for a month or so, but then stopped blowing cold. The pressure reading is now 100psi which indicates a possible mechanical problem. Can anyone advise me as to what might be happening and whether I need to take this in for professional repair?

 

what are both your high and low pressure reading. and honestly if you dont have an a/c licence you could get a large fine for installing r134a to a system. if both your pressures are the same 100 your compressor is not working and the pressures equalized meaning bad compressor.