While I was trying to get my car jumped yesterday, I noticed that when I checked the battery with the charger (harness still attached) that the coolant fans turned on. My engine hadn't been run in the past 2 days, it was ice cold. My electrical engineer friend thinks that I have a bad coolant sensor that'* telling the engine to turn the fans on randomly. This would explain the random drain I've had that'* been killing the battery.

Does anyone know how this system works? Or where the temp sensor is?
Thanks

The fans are controlled by the PCM based on engine coolant temp, but if your AC is selected on, they'll run also. The high and low speed relays are under the maxifuse relay center cover below the WS wiper blades.

Low voltage to a relay or PCM can cause funny issues. Wait until she'* running and fully charged for now.