fan won't come on

Normally, an engine temp sending unit sends data to the ecu. The ecu interprets the data and if engine temp is high it will switch on a relay which then turns on the fan. Being more specific would require more specific info from you. I assume you are talking about a 1992 Pontiac Grand Am with 3.3 v-6?

Ouch. I was hoping nobody would ask that cause it's a 1989 Chevy Celebrity and in order to drive it we rigged up a toggle switch to turn the fan on and off. That's driving me crazy cause it's probably a simple fix - we have a extra car for parts. Thanks for the response........Burr

Find a thermistor for 200 or 220 degrees, hook it up to a relay and replace the switch, stick the thermistor in between the fins of the radiator by the inlet side of the radiator.

The Fan will run when: The A/C is running. The temp hits a preset temp(210-220)and the vehicle speed is less than 40mph. Over 40mph the fan has no effect. Dont depend on the dash temp,they are not that accurate.