It sounds like the issue you are referring to is that your fans seem to be running longer than expected once they kick on I had this same isse with one of my cars,and the cause in my case was quite simple. The otterstat has some hysteresis built into it so that it activates at one temperature and deactivates at a lower temperature (the otterstat is just a thermal switch). In my case, my symptoms were that once the cooling fans turned on they would stay running until I turned the car off. For me the source of the problem was merely that the thermostat and the otterstat had temperature ratings that were not quite compatible. The otterstat would trigger once the temperature got to about a needlewidth above the white tick mark halfway between the 100 and 220 marks on the temperature gauge, and the otterstat hysteresis would keep the fans engaged until the temperature got to slightly below the tick mark. Unfortunately, the thermostat was such that it would never let the temperature get below the tick mark because that was it's set point. The result was that once the termperature rose to a needlewidth above the tick mark, the fans would come on and stay on until the temperature dropped to a hair below the tick mark which would never happen until the car was turned off. The fix in my case was to replace the thermostat. On both of my cars, the fans come on about a needle width above the tick mark halfway between the 100 and 220 mark, and the fans stay on until the temperature drops to about the tick mark (or a hair below). Knut --- In dmcnews@xxxx, Delorean17@xxxx wrote: > Hello, > When my fans come on they stay on for a Long time and rarely turn off. > They turn on exactly on the line below the 220 mark. <snip>