I have a 99 Chevy Blazer. I took it to the shop because of an ongoing problem with the engine light. They replaced the AIR Motor. Since that time I do not get any heat when needed, but when driving down the road I can feel the heat coming through the vents. Did something go wrong when they had to reroute a hose for the AIR motor or is it a problem with the computer climate control? I was also told that the thermostat might be stuck open.