In my 2007 4.3 Silverado, it will tell me on the dash once in a while "Engine hot A/C turned off" even without my engine overheating and wouldn't let me use my AC. As well as the cooling fans cooling my engine below operating temperature because of this. This will also happen a lot when I use the heater. The only way to get the AC going again is to accelerate to around 4000-5000 RPMs. Any suggestions on where the problem could be?