So my AC wont blow cold anymore. (The car is a '99 GTP with the dual zone climate control) I went to discount auto to grab one of those cans of refrigerant to see if thats what it needed. I took the nozzle off of the can to just use the pressure gauge (So I didnt have to buy the can if I didnt need it lol) and went to my car. I started the car, let it idle with the AC set to full blast and non-recirculating. When I checked the pressure in the low side it was like 100psi... My question is "wtf causes that?" I dont know much about AC systems so any help would be appreciated.