My mechanic is scratching his head. Anyone experience this?

Thanks

 

Are you talking it blows heat all the time, or the blower fans won't shut off at all? If it is constantly hot air, check the vacuum lines at the heater control valve and the firewall, and if those are intact, then there is a clip on the control unit itself that tends to break and is a quick easy replacement. If the fans are always on or only blow at one speed, then clean the resistor under the plastic cowl next to the fuse box.