why does the heater click when you turn it on and no heat but fan still blows on 2007 Ford Explorer

The fan blows cold air but clicks when you transfer to heat and heat doesnt come out most of the time. Like something is stuck?????

Asked by for the 2007 Ford Explorer
check your blend door on your heater box fords are famous for broken doors
1 more answer
or the actuator that controls the door