2001 F-150 4.2 AC only works on HIGH
 

Help,
When I have the AC on normal the switch setting on 1,2,3 it blows very little air, on 4 it blows out a lot of air. On AC max setting the is nothing out the 1,2,3 settings but 4 blows a lot of air.
New to the Ford work - any ideas
Bob

There is a resistor block mounted into the ductwork I think under the passengers side of the dash.This resistor "network" consists of if memory serves 3 large wire wound resistors(Coils of heavy gage wire). These are designed to slow the blower speed down when selected by the Cluster switch.
The reason its mounted into the ductwork,is that they produce a good amount of heat when energized,and the airflow keeps them "cool" to a certain extent.
The connector likely has 3-4 heavy gage wires on it,and it should be held in by 2/3 screws.
Find it,unplug it,and pull it out.I suspect you will see that one or more is broken.
New ones are cheap.Dont bother trying to fix it.
The reason HI works,is because in that position,the resistor block is bypassed,and a FULL 12-14 volts are applied to the blower motor.:-drink:-X25
Hope this helps...welcome to FTE