RE: Radiator Fans not coming on 96 Deville
Im not very familiar with caddy cooling systems, but theres usually a relay that is turned on by the a/c control head when u turn a/c on. and another relay that is control by the ecm that turns the fans on when the coolant temp sensor reaches a pre set temperature. (likely around 200 degrees) What I recommend u do first is turn the ac on and look at the fan to see if its operating. if its not operating then figure out where the connector nearest to the fans is and disconnect it. now using a jumper wire, jump power from the battery and a ground to the fan. if the fans working then you know that the problem isnt the fan. its somewhere else in the circuit. check relays, the harness where u can, and check the CTS (coolant temp sensor) its an NTC thermistor which means when tempurature goes up resistance of the sensor goes down. so if theres an open in the sensor the ecm is going to see a sensor default of something like -44 degrees. so if the ecm thinks the engine is running at -44 degrees, its never going to send the signal to the fan relay to turn the fans on.
bottom line it could be a number of things. just go from easiest to check to hardest