My heating fan only works on the high setting Why?

If you have a fan that has different speed settings (1234, or low med high etc) and the only one that works is high - then the blower resistor pack has failed. If you have a climate control unit (where you just pick a temp you want) then the fan is controlled by the heating system and it sets fan speed. If you have climate control style try lowering the temp to a lower setting (current temp in vehicle) and see if fan slows down. If not then climate control unit or fan resistor bad. If dial type and you get nothing on lower settings (only high works like mentioned above) you need to change blower resistor. It is located under dash near the fan itself. Look for small unit bolted in duct near fan with wire plug going to it.

you meant the fan is dead , except on high right.
yes, easy
bad heater resistor block bolted to heater box (fan box)
yes, easy fix. with FSM 10x. easy
or see alldata.com

find the heater box, find a 1 inch cube stuck in a hole in box
with wires attached, bingo 5+ wire? not 2,

I would start with the rear blower motor resistor, the resistor is what controls the speed of the fan, the resistor is located in the rear heater box near the blower, you will need to remove the right rear side panel to access the heater box. start with that

Need to change the switch that works high, medium, and low. It is a separate switch mounted usually behind the glove box or somewhere under the dash. Hope this helps, Mitchell.

When your fan switch is placed in the high position, it feeds directly to the fan motor and bypasses the blower motor relay. If the fan is operating on speed 1-3, then you have one of two things wrong, either you have a blown fuse, or the fan selector switch is faulty on the high setting.

flapper door inside duct work not opening and closing properly. check my tips section for heat diagrams

there is a resistor for the heating and cooling fan speed. this controls the amount of voltage to your fan, which controls the speed. usually when the fan only works on high it will bypass the resistor and use the full 12 volts for the high setting. your power locks might be part of this circuit. i would check the resistor first then check the locks. usually the resistor is behind the high low switch

blower resistor is blown and the blend air doors or motors are broken

check the blower motor resistor that is where the different speeds come from

there is a flapor motor that is controled by vacume, check for leaks in the vacume lines on the engine.