i got my heater to blow air but now i cant figure out why it wont switch the control from defrost ,heater, and vent. could it be vacum? if it is where do i start to diagnose it.
The first place I would check for a vaccuum leak is in the engine compartment. Look for the vac booster and follow the line(s) to the engine and firewall. Then check the back of the controls to make sure everything is tight. Hope this helps
do you have AC/ in truck Does your truck have AC/ if not then it will not be vac, it would be cable for the heater box under dash.
