[GTP Dad]

Welcome to AF! There are two possibilities here. The temp sensor and the fan relay. Sometimes the relay will go bad and the fans will operate continuiously. The other is that the temp sensor sends the wrong temp to the PCM and it turns the fan on. I would change the sensor first and then the relay if the sensor doesn't work. Unfortunately I an not exactly sure where the relay is on the Bonneville. Check in the power control center under the hood but I am not sure if that is where you will find it.