281GT

SCstanger: Thanks for the data logging info. In regards to the low speed on the fan. Apparently Ford was trying to really minimize the energy consumed by the fan. As evidenced by the # 12 gauge wires that feed power to the fan, it's a device that consumes a lot of current. I am going to meter it and I'll let you know exacty how much it draws, but I'll take an educated guess that it draws about 25 amps or more on high speed. There may be cases where operating it at low speed, which is about 1/2 that of high speed would be sufficient to cool the engine yet power consumption would also be about half of maximum which would be around 12.5 amps. While the difference is realitvely small, it would, under the right conditions produce less draw on the elecrtical system. The less work the alternator has to perform keeping the battery charged the less fuel the car uses. I know Ford has done this on most if not all of thier vehicles that use an electric fan as an energy conserving feature. It would be difficult to tell in you fuel consumption the difference, but add this in with other things that are done to maximize efficiency you can have some significant differences in efficiency between this and a car that does not have these features. As far as Ford is concerned, adding a two speed fan is simply a few extra bits of code in the computers programing instructions and a two speed fan relay. It's very inexpensive for them.

In regards to why C&L (that's the same tune I started with) decided to have the low speed on the fan come on at a temperature that is lower then normal operating temp for the engine is beyond any logic I can think of. I have a theroy though.
I think they based this on their incorrect assumption that the fan will not operate at speeds above 30 mph. IF this was corect, they would be garanteed a very stable cooling system that would virutally never exceed the normal operting temperature because the fan would never cycle. It would just run continuosly at speeds below 30 mph. Not a bad situation.. The problem is that the fan does NOT shut off at higher vehicle speeds and of course all this does is waste energy, hp, gas, ect. I had no idea this was happening until I connected an LED to the fan using a relay and discovered that the fan came on just prior to the engine reaching normal operting temperature and stayed on regardless of road speed. Certainly not good. BTW, there is a reason I used a relay to drive the LED that I'll explain here. The fan uses a D.C. electric motor. A D.C. electric motor when rotated by another force, such as that which would be encountered by wind turning the fan blade at speed, would cause the fan motor to act like a generator. This would cause my LED to light when there was no power applied to the fan, thus giving a false reading at speed. So I used a relay that energizes a set of contacts that routes power to the LED from a source other than what powers the fan. This way I could be sure that my LED fan indicator was giving accurate readings.

At any rate, I think thats why you C&L tune had the fan set to come on at such a low temp. They wanted it to run constantly at speeds below 30 mph for a very stable cooling system. Too bad they were wrong with the idea that the fan shuts off at speed above 30 mph.

TinPony

281GT.... I really appreciate your time on this thread, you have provided a tremendous amount of good info, I would like
to see that wiring diagram of the LED/fan on indicator.

281GT

TinPony: I'll post a circuit diagram here so you an others can do the same. I'll get it done either tomorow or the next day.