The compressor will come on and cool as long as I have the fresh air door open and the fan selector set to high. If I shut off the truck the compressor will not engage. If I have the fan set to 3 or lower it will cycle off but will not come back on. If the fresh air door is closed the system seems like it freezes and turns off. In all of these situations the ac will stay off until I shut the truck off and let the engine cool back to ambiant temp. On a 100 degree day the compressor will not engage at all......Help

 

I want to add that today after running the engine and heating everything up, I shut off the A/C then tried to turn it back on. The compressor would not engage, I jumped the relay across the 87 and 30 pins. The compressor still will not engage.