this isn't in my truck but in a focus.......if the a/c only works on 4 and not on any other setting does anybody have any idea what could cause that? thanks for any ideas

 

setting 4 is high and is run by a relay (full power). The other settings are run through resistors to lower the voltage and hence the speed of the blower motor. Check the connection to the resistor pack usually mounted on the a/c box itself or the connections at the back of the control panel. Check all of your fuses first before you start troubleshooting.

 

The blower resistor is mounted into the fan housing so cool air can pass over it and keep it from overheating and burning out as yours probably has. The resistor has a harness with four wires plugged into it and is a phenolic strip about 3/4 x 2 inches that is attached to the blower housing with two screws. It is not unusual for them to fail and you'll probably be best off getting one from your local dealer. Once you have it, you'll see where it goes. It should take you about two minutes to swap it. The one in my truck is a pale red color and looks like it is made out of fiber board.