QuestionI have a town & country LXI 1998. My A/C button and the recirculation button blink simultaneously after starting the engine for about 15 mins. What could be causing this?
AnswerHi Lee,
Another visitor to the Allexpert site saw your question and passed along some helpful info that I wish to share with you.
"Hi Roland,
No question. Just passing on to you info for the person with the Town &
Country with the two lights flashing on the HVAC head unit. This is a
fairly common phenomenon on the 96-00 minivans.
To make it stop, you can just make the body control module run the
diagnostic sequence. You start the engine, setting temp to cold, with fan
on high, and pushing the rear wash and rear wiper buttons at the same time
and holding them until a bunch of lights start to flash.
It takes a minute or two for the tests to cycle through. It'll run the
calibration/diagnostic test (2 lights flashing) then the cooldown test (2
other lights flashing). If all passes, the rear wiper switch will flash
alone. Push it to exit tests.
If it fails, one of the lights on the head unit will flash out a
diagnostic code, just like the OBD does with the SES light. There's about
six pages in the Chrysler manual about what the HVAC diagnostic codes are,
but I have no clue what they are. I don't own a manual, but it was shown
to me once.
Your advice was correct in that the questioner's HVAC system is probably
fine. However, this phenomenon of the lights flashing can happen when the
BCM experiences a spike or dip in power. You might want to ask the
questioner if he recently removed or replaced the battery, or something in
the charging system. If not, he may want to have his battery and/or
alternator tested. He could have a dying battery, corroded terminals, bad
ground, failing battery cables, etc., etc.
The BCMs in these vehicles, I have found, are very similar to the computer
in your home or office, in that they like clean, steady power, and begin
behaving badly if there are surges and power losses. Also, a soft reset
of the BCM, by pulling the IOD fuse or negative battery cable for five
minutes will clear out anomalies, glitches and other little hiccups, much
the way a reboot will free your home or office computer from being caught
in a data loop."
That was very helpful info which I too will copy and share with others as the need arrises.
Roland
Hi Lee,
I suspect that the control unit is exhibiting some aspect of its self-diagnostic capabilities for finding faults in the system. But unfortunately none of the manuals that I have speak to the specifics of this test protocol procedure and its interpretation. It is no doubt covered in a Chrysler body computer manual for the van of that time frame but I haven't found one for sale that is fairly priced. I will keep looking and let you know when I find one. If the A/C and heating functions seem o.k. I wouldn't worry about it.
Roland
