Chrysler Repair: T/C : A/C off in reverse, ABS-Brake warning on, amp fuse, haynes manual

Question
Hi Roland,
An odd thing is suddenly happening to our 98' Town & Country. The van starts fine (with A/C on), but as soon as we shift into Reverse the A/C completely shuts off (blower, compressor etc).
If we shift back to Park or shift to Drive, then the A/C comes back on again.
I also found, if I press the "Rear Defrost" button, the A/C shuts off then as well.

Also noticed the "ABS" & "Brake" dash lights are on now too.

Any idea's?

Thanks,
Guy

Answer
Hi Guy,
Unfortunately I don't have complete wiring diagrams for '98 so I can't look for a common cause for all those malfunctions by examing the + side wiring design. However there is one fuse in the power distribution center under the hood near the battery that powers both the back-up light circuit and the A/C blower relay (and possibly therefore the compressor too) which if it had a crack in its internal conductive wire might overheat and temporarily open when the back-light were drawing extra current, and then close when you shift out of reverse (check to see if the back up lamps aren't working when you are in reverse). This is fuse #12 (10 amp) so take a look at that fuse to see if it has such a crack or is loose in its socket. You could also try exchanging that fuse with another 10 amp fuse to see if that solves the problem. If it does then replace the 10 amp fuse. I wish I had a full set of diagrams but this is one possibility I see from studying the Haynes manual for the van.
A general possibility too is that one of the ground paths from all these affected circuits is flakey and opens due to vibration or stress from going into reverse. I would look for a loose ground connection: specifically in front of both the left and right side front door openings you will find a couple of bolts (possibly hidden by a trim panel) near the floor that hold several black or black/other color wires fastened to the metal of the cowl panel. Check those bolts to make sure they are tight. Many of the controls for these affected circuits ground at either of those bolts. The last possiblity is that some water has gotten on the plugs to the body computer which is located next to the underdash fuse box. If any rain water drips onto this central computer for electronics related to the body you can get some strange gremlins due to shorting out at the plug sockets into it. So you could pull those multipin plugs and check for water, corrosion, dirt on the pins and the sockets. Clean those with spray electronic circuit cleaner from an electronic supply store.

Please let me know if any of these suggestions solve the problem.
Roland