Auto Air Conditioning & Heater Repair: AC not very cold, diagnostic work, uv detection

Question
The AC on my 1995 GMC Sub. is not cooling very well. It has some cool air coming out of the vents but not cold enough to cool the truck. I put my gages on the system and the pressure readings were 65 on the low side and 250 on the high side. Out side temp about 90F. Thanks for any help you can give.  ?????

Answer
Paul,

The pressure on the low side is low at 90 degrees the pressure should be at 104 psi. This problem will require some diagnostic work which mean you'll have to determine if you have a low charge in the system or a restriction on the low side. Its more likely that you have a leak in the system and to find the leak you should charge the system with the freon that has the uv detection dye and with that get the uv light and goggles kit and check it after a few days of use.