I have a Black 2007 sxt dodge nitro 3.7 engine 2 wheel drive. The car looks like new after doing a lot of work on it. The only thing left is my A/C. The A/C is not cooling enough. I charged the low side to 50 psi . I can't check the high side. The air temperature coming from the air vents is about 65 degrees it should be 35- 45. The clutch is working on the compressor. Any ideas where I can checked to see what's wrong???