Sometimes I cant get cool air to blow out of the vents. When I slide the dial down to blue hot air still comes out. Even if I turn on AC its still hot. The only way to get it to switch is to kill the engine and restart. That works ALMOST everytime, but even so sometimes if I slide it back to warm or hot, I wont be able to cool again. When I do have cool air blowing there is a bubbling or knocking sound. I've already had to replace blower motor resistor and connectors for other reasons, and have check engine light on now cause computer is incorrectly reading gas valve not closing.
