Crazy AC Question

[Agentlongwood]

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.

[TheOtherNick]

Could be a clogged up Orpheus tube, ac fans not working, plugged up condenser fins or the condenser ion the inside plugged up. Make sure the fans are working both should be on with the ac on then blow out the fins on condenser.