'96 Taurus electrical problems

[JMWallace]

I have a '96 Taurus with all kinds of electrical trouble. Any mechanic I've taken it to can't seem to find the problem and I'm thinking that some of these things have to be related. Just to mention a few: My odometer has stopped working, no A/C, no heat, no rear defogger, the interior lights that go on when the doors open will not go out, the battery drains after sitting overnight or after sitting for any period of time and there have been problems with the rear windows not operating. My radio/tape player is not working at the moment and my current mechanic seems to think it has something to do with a part that contains radio and A/C electrical connections that costs approximately $800. I've had these problems for a few years now and don't have a fortune to spend on diagnostics. Any mechanics I've had don't seem to think these electrical problems are related, but how can they not be? One told me that they wouldn't bother spending the money to look into it any further. Any ideas? I'd appreciate any input.