Autosport Labs

I have come up with a really simple idea for fan control.

With my car as long as I am moving / driving the fan does not need to be on. But when in traffic (stop and go) obvious it does so I was just going to hook up one of my fans so they will come on under say 1800rpm. I would then hook up my 2nd fan to come on over 4000 thinking that if I am romping it that hard I probably want the added cooling. The only thing I am thinking is I may want a relay that will only trigger after say 5 seconds since when I am rowing though the gears it would keep the fan from cycling or it would allow me to set the threshold higher to say 2000. My typical cruising RPM is about 2200.

This seems to be a very simple way to deal with the fans. I currently have complete manual control of the fans so I would just replace the the toggle switches with three ways that would have off auto and on keeping the al control but letting it run in auto as needed. I would also put a led on it that would be red the fan is off and a green when in auto mode and a yellow when it is in the on mode each fan has there own toggle switch as well as its own set of LEDs.

This seems to be a simpler way to control the fans and my experience with my car is that I really only need them on when at idle or off idle in traffic.

I noted that the air conditioning condenser gets no airflow when sitting still & engine not overheating. So a sensor runs the 2 fans slowly wired in series anytime the condenser gets hot. If the engine temp gets above the point where thermostat is all the way open, they also run in series. Hot engine of course runs the fans full speed direct to battery, and keeps them on after shutdown till temp drops some. Bruce Roe

He he he AC?????? My car shed that for weigh savings back in 1993 or 1994 I think. If I want it cool I have to drive faster. It also drastically reduces cell phone usage as you can not hear a darn thing when you are "at speed" with the windows open

You could also include a timing circuit into the equation to provide a bit of hysteresis into the circuit so your not turning the fan off and on alot when accelerating and slowing down in a traffic situation otherwise the life span of the cooling motor could be reduced due to continuous switching. A vellerman kit might be a good idea for this as they do monostable and bistable kits if my memory serves me right and could included into the circuit.

In honesty i think the OE fan control switch should be able to cope with the switching of the cooling motor more than adequately and there is no real need unless one would like to play around/tinker with the system.

To do it ideally they way you wanted a road speed sensor would probably be the best solution and comes on when the vehicle has stopped. Maybe look at the ABS for an output signal when the car is moving or not for a better solution (if you have ABS that is).

Surely you want the fan off even on idle when the engine has just been started. A wait of 5 minutes or so before first operation might fix that, but then how would you deal with a hot start? Remember that cold running is when the bulk of engine wear happens.

What's wrong with a thermo-switch.

Oliver Sedlacek wrote:What's wrong with a thermo-switch.

Nothing.. . . I am just trying to be different. I have relays, I have the MJLJ, why not?. Actually controlling your cooling fan via a temp switch is so yesterday. MJLJr can do anything.. . . world peace, global hunger are soon to follow. If I can just get it to control my cooling fans LOL

I think I need some quality time on the garage. This work thing is making me a tad nuts.