i have a 1999 Chevy Silverado with the 5.3L. I will have the heat running as high as it can go and it will just randomly switch to AC and i will have to turn the truck off and restart it for the heat to work again any ideas? Also I have about a 30min commute and will leave the heat on the whole time and it just don't seem like it will ever get hot enough it just warms up the truck?
