my heater,windshield wipers, and my cooling fan only come on when they want to...if you turn the key off and on eventually it will come on...if you play with the wires just right on the drivers side firewall you may get lucky...i was wondering if this had occured to any one else with a '90 323...and if so...HOW DO I FIX IT????

Try slowly wrigling each wire (one at a time) moveing along its length, get someone to watch the wipers for a response if you can't.
Then you can concentrate on the wires. When you can make it stop and start at will that is (most likely the faulty one). there may be more than one poor connection, check all crimp lugs for tightness , you may be able re-crimp the old lug, also check all plugs electrical and battery connections for tightness and keep an eye out for damaged insulation which could cause a short circuit.
Good luck.

I had the same problem.
Check the ground cable lug before the battery.
This lug are mounted to the body and the cable pass throu to the battery.
Good luck
Danie