Chrysler Repair: 99 T&C:rear defrost/rear wiper/HVAC air distribution problems, check fuse, airflow control


Question
QUESTION: Hi Roland,

I'm back, the clockspring under warranty fixed my intermittent air bag light and lack of steering wheel controls. While waiting for that to get repaired another electrical gremlin surfaced. I now have no controls for the rear window defrost, wipers , airflow control etc. The fan works but that's it in the center area. I checked rear wiper fuses and a few others. What are your suggestions as far as troubleshooting?  To refresh your memory all this started during a massive deluge and the drain for my wiper leaked straight onto my alternator shorting out the electrical system. A dry out and recharge of the battery fixed it and then the gremlins started again as it had problems when I first bought it that was fixed with the speedo logic and ECM replacement. Thanks again for all your valuable insight and experience.   Richard

ANSWER: Hi Richard,
Because there are separate supply fuses for the problem circuits at the HVAC control panel, the common factor for the rear wiper and rear deftroster (and probably for the airflow controls as well) is the grounding wire from the blue plug on the rear of the HVAC control panel at pin 21 (black/light green) that goes to a multiple wire grounding fixture that attaches to the center support of the instrument panel under the dash (that wire attaches to pin 5 of that fixture). So I would check both ends of the black/light green wire for possibly being loose/corroded as the result of the 'deluge' and also check the continuity of the wire itself between those two ends.
Please 'rate' my answer (see below).
Roland

---------- FOLLOW-UP ----------

QUESTION: Hi Roland,

Sorry for the weather delay but I have that out and I do have continuity at the black not blue plug into the back of the a/c controls. Next step? I'm going to see if I can pull up a schematic so I can follow along Thanks, Richard

Answer
Hi Richard,
Check fuse 6 under the dash and look for a possible subtle crack in its wire.
Then look at the circuit board inside the HVAC control, specifically look at the trace beneath the top temp slider as the current from fuse 6 arrives at pin 10 of the control plug and  then goes to the circuit board inside. Check that you are getting 12v at the circuit board from pin 10 of the plug when the key is in the 'run ' position,  and then follow the trace to any other points on the board connected to that incoming 12v to verify that there is not a break in that trace. This supply from fuse 6 is what powers the rear wiper controls/air flow control/defrost. I have pencilled in to my wiring diagrams that another owner found a problem in that trace.
Please 'rate' my answer (see below).
Roland