Chrysler Repair: Town and Country-Electrical mayhem, screw out, windshield wiper

Question
My 2000 Chrysler T&C---All of the sudden, A/C will not engage, Speedometer quit working check engine ligt comes on.

In the past the windshield wiper speed function quit working then just started working again after about a year. I mention this only because it could be related.

thanks

Answer
Hi Glen,
Frustrated, I reply again after composing a brilliant answer and having the internet connection break down!
The check engine light came on because there is a problem that effects pollution from the tailpipe and that problem is no doubt the loss of the speed signal to both the dash and to the engine controller. The speed signal comes from a small sensor located on the side of the trans that faces the front of th van at the extreme left (driver's side) end of the powertrain, about midline in the trans. It has a two-wire connector (dark blue/black and light green/white) so inspect the disconnector and the wires. If there are no problems with those, then a new sensor will probably repair the speedo and the light (though it may take a while for the light to go off, unless you disconnect the battey which will kill some of your radio presets, etc. Wait for 50 or so engine on-off cycles and the light should go off if indeed the new sensor gets you back the speedo). The sensor is a simple screw out/screw in item from a dealer (though not cheap).
The A/C usually fails due to low refrigerant pressure which means a refill and that can be determined by an A/C shop. About the only other possibility for both the A/C and the wiper history is that the body computer (yes another computer) located on the back side of the fuse box under the dash has gotten wet and has some short circuits at its several plugs. Have you had a history of water leakage around the windshield in that area? If so it would be worth buying a spray can of electronic circuit cleaner and removing the body computer plugs so as to spray the sockets and pins on the plugs to evaporate any water or remove short circuits due to crud. I often call that situation  a case of gremlins, but your term mayhem is good too. Otherwise, if the A/C recharge works, the wipers now work, and speedo comes back... you are good to go.
Let me know how this works out for you.
Roland