I'm about to buy a near perfect 1992 Coupe DeVille with 79,650 miles. What's troubling me is the fact that a fan for the AC system I think won't turn off when I shut the car off during the test drive. The owner is puzzled by it too, since this is the first occurance he's known of it. We tried unhooking the battery, waited 30 seconds and then reconnected it, but it turned back on. Please help, as I would really like to buy this car without having to spend a huge amount of cash,figuring out what the hell is wrong with it.

 

Unplug the fan control module. Its under the hood on the firewall.

 

Where exactly is that, like (left or right side) or whatever. A diagram might help me too, as I don't know what the module looks like.

 

My 1989 De Ville had the same problem and it drained the battery down flat. Clean the battery terminals, turn the ignition onand with a multimeter set to the 20V positiondo a load test on the battery to determine if the voltage is in the range of 12 to 14 volts. It should not go below 11.5 volts. Wear safety goggles when working on the battery.
Sufficient power is necessary for all electrical systems to function properly. Make sure that before you disconnect or reconnect wiring to first remove the negative battery cable to protect the delicate electronic circuitry.

 

It must be the module because it has a brand new battery.