1992 Mercury Marquis compresser

Air Conditioning problem
1992 Mercury Marquis V8 Front Wheel Drive Automatic

my air compresser will come on then stop come on then stop Everybody keeps telling me I need to add some refrigerant but the accumulator want take it in. The unit is blowing nice and hard on the inside it not blowing hot air but it want get cool at all Then on top of that if I try to run the air while driving the car cuts off