2kwik4u wrote:...The fan does control temp to some degree. If you pull more air over the same surface area, you increase the cooling efficiency of the radiator, and make the coolant cooler. When mixing the hot coolant from the engine with the cold coolant from the radiator, the difference in temp is what determines the final temperature.
You have the right idea, but perhaps some misconceptions, or just the opportunity for someone else to get the wrong idea. I just don't want the latter to occur.
Yes, the fan does control the temperature to some degree. But only after the thermostat is fully opened and the radiator is unable to dissipate the heat without the assistance of increased airflow. The radiator does not get "cooler" . Its efficiency is indeed improved and a greater amount of heat is transfered to the airflow. That is just mincing words. I just want the process clear.
The thermostat does open and close to control the temperature. It alone controls the temperature until the full open position is achieved. After that point airflow and the radiators ability to transfer the heat are the controlling factors. Ideally the radiator and fan should be sufficient to never require the thermostat to be in the fully open position continually. That would be operating too close to the edge and the potential for overheating might exist.
Could you use the fan to control the temperature alone? Yes. Race cars use a restrictor in place of a thermostat sometimes. The fan is used to control the temperature. This is a very controlled situation and not subject to the rigors of a street driven vehicle.
Would I want to rely on fans to control temperature? No.
The whole system needs to work together. It feels a little ridiculous to argue that the fans do not control the temperature, but when we are referring to the low side and low coolant temperatures, the fan really does have no ability to make changes. the thermostat is the only temperature control on the low side.
Consider a boat. It has no fans and a reservoir of , sometimes extremely cold coolant. The thermostat is the only temperature control.