I have the original Frigiking system on my car with the York compressor. It uses R12 refrigerant which is much more efficient than the newer refrigerants. This means, if you change, it won't blow as cold. The compressor is a piston type, meaning the volume it pumps is proportional to the RPM. The newer Mercedes compressors have a changing volume so that even at idle it pumps cold. When you use the A/C with the top down the cooling effect is barely noticeable and it is a waste of H/P to operate it with the top down. If you want working A/C you must use the newer rotary compressor with a solenoid to keep the idle speed up. The A/C uses about 5 HP but the York compressor uses very little power at idle because it doesn't pump much so the existing solenoid is adequate. If you run the newer refrigerants the expansion valve must match. You may want to inform yourself of what is involved and make sure you speak to an expert.
