Chrysler Repair: a/c - heater fan not working, intake plenum, screw heads

Question
I have a 93 Chrysler Salon New Yorker.  Recently while driving, my heater stopped working on all settings but high.  (when set on low-med, nothing happened, not even the fan blew).  Then, all of a sudden the day after, it stopped blowing any air all together.  I had a friend look at the fuses (they were okay), we attached the motor to a battery (it worked) and I even replaced the control box.  NOTHING has worked so far.  Do you have any suggestions?  Winter is just starting, and I dont want to be left in the cold!  Thank you!

Answer
Hi Kimberly,
I think what has happened is that a heater resistor block module has failed. What you described is exactly what happens when this unit fails. This is an array of resistors that changes the voltage supplied to the motor as you change the setting of the fan switch. It is located in the area called the plenum of the air intake, which is on the outside of the car, just in front of the windshield on the passenger side of the car. (Basically it is mounted on the  cowl, behind the glove box.) You will see a screen over this area to keep leaves from getting into the air intake. You probably have to lift the hood up to see this area. If you look thru the screening with aid of a flashlight you may see it inside that area, screwed to the back wall of the intake plenum where it will be cooled by incoming air. If you remove the screen it may be more visible. It has about 4 resistors on it. Now I am not certain if it is held in place by screws from the plenum side, or if it is held by screws on the inside of the car, behind the glove box amd is removed from the inside. Look at the mounting screws and see if they have heads on them, or just the pointed ends of screws projecting out. If the screw heads appear to be on the inside of the car, then you have to unscrew the screws that go around the glove box door and take the glove box off to get at the block from inside the car (You also may have to remove a panel at the lower edge of the dash, under the glove box).  You remove the screws that hold the resitor block in place, and you will also find on the backside of the block an electrical disconnect plug. Get a new heater resistor block from a dealer or if it is too expensive go to a junk yard and find a similar one on a Chyrsler New Yorker or similar higher priced wreck. In fact, you can practice your removal technique on the wreck if it is a pull-it-yourself wrecking yard. Just plug in the replacement, remount it, and your fan will work again!
Roland