AC shuts off HELP!!

[spd1235]

My AC works great when I first turn it on. It runs for a few minutes...sometimes half hour or more on the hwy then it shuts off. I can turn the AC off and let it set a few minutes and then turn it back on and it works for a while...and so on...
I put a gauge on the ac and added a can of coolant. the pressure was at 40lbs when i hooked it up and after the can was put in the pressure was only 46-47lbs. ac still does the same thing. and i dont know if its related, but my engine ran hot the same day and it never did that before.

 

[DirtJack]

I have a similar issue where it will work for awhile and then stop working. No hard accelerating on my part. Seems to work longer when the weather is cooler out when the AC is not needed. Is there a sesnsor that shuts off the compressor if it gets too hot in the engine bay?