Its not a set of gauges. Its the cans of freon you get at wal mart with the pressure gauge on it. It only goes on one part of the AC. Different size fittings. It goes on the part of the hose thats toward the passenger side of the engine compartment closer to the firewall. Thats the high side correct? Im not sure what the problem is. My AC hasnt worked correctly for about a year and a half now. I got a can of freon last year and it seemed to pull it all in and ran much colder when I did it but it did take a while for it to use the whole can. The car has never had any other AC problems and I dont hear any kind of pressure relief occuring so I dont think its got a leak but I could be wrong. How long does it normally take for it to use the can of freon?