Chrysler Repair: Smoke !!! Chrysler T&C 1998 heater problem, chrysler town and country, internal circulation

Question
Hi Roland,
Found your name while trying to find some help regarding a heater problem with our 1998 Chrysler Town and Country LXi. Had the van idling to warm up on a winter day (25deg F), heat and fan at max, internal ciculation on. When I then got into the car to drive off, I switched the internal circulation to off and almost immediately got the smell of an electrical fire with some smoke. Turned everything off and switched cars for the day. Have since been trying to narrow down what could be the cause, not completely with success. I thought initially it could have to do with the aux heat unit (German model - I live in Munich - gasoline driven, 4kW), so I unplugged that connector. However, it seemed that I still got the smell of overheated insulation/electrical smoldering when I turned on the blower, however, only when the (car-)motor was running. It seemed not to be there if I just turned on ignition and the fan motor. Since, I have run though several different configurations (different fan speeds, driver and passenger side to hot/cold, switching the airflow direction to different settings, etc.), and somehow the problem is gone. Can't get the smell of electrical smolder any more - which I like but don't trust, as I have no idea what the origin of the problem was in the first place. It does seem that the airflow at max fan speed is not very good, and I wonder, whether there might be some blocked airflow (?from the outside in??) or stuck valve (I saw from your previous response to 'Kate' that there is some kind of diagnostic sequence one can use). But how would this result in overheating of some electrical circuit or motor and why does everything seem to be OK now. Maybe you have suggestions of how I should proceed.
Thanks for now and greetings from wintery Bavaria.
Mike

Answer
Hi Mike,
One possibility is that there was a short circuit which didn't blow a fuse but which overheated some wires or the blower motor that resulted from getting rainwater into the system. One preventive measure to reduce such intrusion is to but the system on recirculation air flow pattern before turning off the engine.
Smells from melted insulation are fairly persistent even after the original overheat has ended. So if it is gone now and not recurred I would believe that the problem no longer exists and that deteriming the original cause would be more time comsuming and possibly costly if you go inside to find it. Another possible explanation is that there were some leaves that had gotten into the system thru the air intake and that those caught fire. You could also check the air intake plenum for a build-up of debris by removing the grille in front of the windshield and cleaning it out.
So those are a couple of thoughts on your current situation.
Thanks for the greetings, here in California when we get into the 40's(F) that is wintry.
Roland