I have a 2011 F-250 6.2. A while ago I was having issues with my a/c blowing cold air. It would blow cold air about 15% of the time it was on. I was told that I might have air in my lines. So I set it up to vacuum it out and then recharge it. I did all of the right steps and started to refill it. I could get about 1/2 pound of Freon in it and the low side would shoot up to 90 psi and the high side would only be 120 psi and the compressor would never kick on. And when it would work before the compressor would kick on every now and then. The temp outside was 99 when I did it. Any ideas on what it maybe could be? I know taking it to a mechanic would be expensive but if I need to I would. Thanks for the imput......