cooling fans

My fans are not working that are on the radiator. Where or what is the first thing to check? Sensor, switch, etc. And where are they located?(sensor, switch, etc). Thanks,
2001 Malibu 3.1

are u sure they are not working cuz the wont turn on untill about 228 F

If the fans or fan system (relays & switches) aren't working correctly, your check engine light should be on....

Try replacing your coolant temp. sensor. I "blew" mine when I didn't drain the air out after changing the thermostat and the car over heated. It's fairly cheap ($13 @ autozone) so even if that's not the cause you know at least 1 sensor is brand new.