Hello all...

A couple (Jeff & Jeni) who are friends of mine purchased a 1998 Dodge Caravan for a very reasonable price. It has the 3.8L V6 with 190K on the clock and runs & drives very well.

It is however experiencing a very strange problem. Whenever certain electrical devices are turned on, the A/C stops working and cannot be made to work! The Blower Motor Stops and the A/C Compressor kicks out as well. Most noticeable is when the vehicle's tranny is placed in Reverse. Other things that shut it off are attempting to switch on the Fan for the Rear of the Vehicle, or trying to make an Adjustment to the Driver's Power Seat. (There are probably other things that set it off as well, but not being all that familiar with the vehicle, I don't know what those items are at the moment.)

Relays and fuses have been checked and seem to be functioning properly. Jeff and I swapped in a different Battery, but resulted in no change. I tried to follow the ground wire from the Battery to the back of the Block to see if the connection was loose or corroded, but the engine was still very warm while attempting this, so I didn't get to perform a very thorough check.

One other quirk this wonderful machine is experiencing is the Rear Hatch will not Lock, but the vehicle's BCM continues to attempt to lock it and will drain the Battery if its allowed to do so. To remedy this the fuse that controls this feature has been removed. I haven't yet tried replacing this fuse to see if this fixes the A/C Problem and this will probably be our next step.

If anyone has any information that may lead us in direction to solve this problem your insight would be most appreciated. Thanks a lot everyone.

 

I would bet you have a corroded/loose connection in the primary power bus somewhere. Ya, but where?

> Inspect the PDC connections and both the +/- battery cable connections at the ground point and the PDC. Battery cables are known to corrode internally causing power issues. Try a shake test on them watching for any indications of a power flux in the lighting or any system that's running.

> Test the alternator output. Connect meter leads across the battery terminals with the engine at idle. Should see at least 13.5 VDC. Shake any accessable wire harnesses making sure the volatge stays steady. Wouldn't hurt to have the alternator tested.

> Inspect any wire harnesses for chaffing or heat damage especially those routed near the intake and exhaust mainfolds. There's two in particular that pop up on forums. One routed under the battery tray and another routed under the engine near the transmission. A shake test may reveal the culprit.

> Try voltage drop tests. Here's how: http://www.aa1car.com/library/voltage_drop_testing.htm

 

I'll add your suggestions to the list. Thanks very much for the reply.

 

down at the bottom pivot bolt for each side of the instument panel is a ground wire that connects the panel frame to the body. Make sure they are good and clean. Also make sure the pivot bolts are tight.

 

I'll see if I can find these Pivot Bolts as well. Thank you.