Chrysler Repair: AC-Heater Issue, side kick panel, chrysler lhs

Question
My Chrysler LHS 1995 has a AC-Heater Issue.  When I start my car, invariably the ac and defroster lights are on.  I have to turn them "Off" and then reset my temperature and controls again.  This happens each time I start the car. It was a nuisance until now.  After 5-10 minutes the ATC display lights will flicker and then go off completely.  The blower then blasts "HOT" air.  I can't turn it off.

I read the ATC codes and Code 36 (Head Communication Failure) is displayed.  Is the unit shorting out? Do I replace the unit or just the Blower Control Module.  Help...!  Getting cooked with hot air was fine in the winter...but summer is fast approaching...!


Answer
Hello Darlene,
The communication failure proably means that the communications signals either too or from the ATC control unit are not being received at the body control module. This may be either due to a wiring problem or an electonic problem with the ATC control unit. You can check the wiring out yourself with a volt-ohmmmeter. Begin by checking for blown fuses in the fuse box that are in anyway related to the heater/AC or ATC unit(location of the fuse box is described below).
If the fuses check out, then you can remove the module from the dash (I believe you merely remove the bezel that surrounds the console and then you'll find the screws that retain the control module. Remove the screws and the module should slide out). You need to look at the plugs on the rear of the unit. On one of them, in position number 3 and 4 you will find a violet/brown and white/black wire respectively. Check the plug for any corrosion. Then go to the body control module which is located above the passenger side kick panel (the panel to the right of the front passengers right shin) where you will find a umit with two plugs on the top, and on the bone colored plug you will find the other end of those two wires on pins 8 and 7 respectively. Use your voltohmmeter to verify that there is continuity between both pins on the ends of those two wires (e.g. 0 ohms resistance reading). Again check the plug at the body control module for corrosion. If that all checks out, plug in the plugs to both units and see if that has solved the problem. {There is a second plug at the ATC head that has two pins. Check that the black/pink wire has 12v on it when the ignition switch is in the run position. If not check for a fuse that may be blown, in the fuse box (location is described below).}
If that all doesn't solve the problem, then you may be able to open up the electronics of the ATC control head and find a damaged component to replace, or if not then go to a junk yard in search of a replacement unit of similar design and year model. In the meantime, to avoid being roasted, look under the dash on the driver's side of the car and at the far end you should find a fuse box with a key table to show you which fuse powers the ATC control or the blower motor. Then pull out that fuse.
Roland