Why does the fan for heating and cooling only work on the highest setting in your 2001 Mercury Villager?

If the fan in your 2001 Mercury Villager only works on the highest setting, it’s likely due to a faulty blower motor resistor. The resistor controls the fan speed, and when it fails, it often defaults to the highest setting as a safety measure. Another possibility could be a problem with the fan switch itself. Checking and replacing the resistor or switch should resolve the issue.