AC won't stay cold
 

I'm trying to trouble shoot what is causing the problem.

04 coupe

I put a AC pressure tester on, and no matter how hot it is outside, it stays betweenn 35-45psi. I used the dye to see if I could find a leak....no leak detected. If the ambient temp is below 75, the AC is cold. but anythinng 80+ it blows cool. The compressor comes on without a problem. I have not found any signs of any leaks, not even in the cabin. I have recharched the system and i have no change. one thing I noticed, that i am not sure if its normal or not, is that the low side of the pipes gets really cold, but the high side actually stays warm. any suggestions will be appreciated

I bet its your heater box

mine wont turn off!...LOL

Care to elaborate more