I have a 2000 NISSAN Quest. This is basically the same thing as a Mercury Villager. The fan for the Heater/AC is starting to fail. The switch is a rotay knob with 4 positions. (1,2,3 and 4) I think position one was always off, but about 2 weeks ago, position two would not work. Then yesterday, position three stopped working. Position 4 still works but this is at full power.

I guess it could be the switch, but does anybody know how I could test this? And is there somehting between the switch and the fan, perhaps a relay of some type?

"Update" - From reading other posts on this site ,it may be a 'blower resistor'. I know it's behind the dash but does anybody know where on this van? Any more info on how to test it?

 

This part is located under the dash (there is no need to remove anything - lay on you back and look up the underside of the passenger side dash).

You should see a hex head screw (5/16") holding in a rectangular black plastic piece (about 3/4" x 5"). There is a four connector plug attached to this piece. Remove the one hex head screw you can see and feel for the other one behind the piece. You can remove the 1 inch rubber hose to gain access.

Once you get it out look it over. Mine had a big black burn mark on both sides.

The dealer wanted $40. I found a nissan parts place on line that wanted about $9 (plus shipping). The fan still works (albeit at full force only) with the resistor removed so I waited for it to come by mail.