Originally Posted by Tivs
Did it just stop? or did u just purchase the truck. If u just purchased it maybe someone did a ball valve mod...hell if uve owned it and it just stopped ive seen the ball valve clog up acting like its closed causing no heat.
Tivs, where is this ball valve? I was going to suggest checking to see if both heater hoses where hot. If so a possible blend door not working. I don't know if they are vacuum, but mine must be because it is all knobs no sliders.