Les Manse

This has me puzzled: My 1999 ES300 has been perfectly normal in every way (60k). Yesterday when I turned off the ignition the radiator fans both started running and would not shut off as long as the ignition was in the "off" position. When in the "on" position everything is well, and the fans don't run. It is winter here, so there is no reason for the fans to run at all. In order to shut them down and save the battery, I had to pull both fan relays. Anyone been down this road? Les