Run a light from the fan?
 

Re what is too hot:

Can I run a light or led from the fan so it would indicate when the fan is running? I don't think it would interfere with normal operation. Plus it would be really cool to have a bunch of lights and switches on the dash.

Absolutely. You can also run it from the fan control relay.

This might be handy for selecting a load limiting resistor: LED calculator for single LEDs

I did this on my festiva. simple wire with frame ground and a resistor in series with the wire tapped into the fan plug. I'll check tomorrow what value i used if it's not raining, but i think i used either 1k or 4k7, not 100% sure. considering doing the same to the dezlbug

I wired an LED to my fan's supply and it was on whenever the engine was running. It turns out that the fan in my car is not an ON/OFF affair, there is always some residual voltage and the speed is regulated by controlling the current (yes, the speed is smoothly increases with temperature). So until the coolant gets too hot there's not enough current to start the fan, but more than enough for an LED to shine. I've pondered about how to overcome this problem (bigger resistor? add a relay? inline ammeter?), but then desided that the fan is loud enough to be heard over my diesel's clunk-clunk-clunk anyway, so I gave up.

yes, there few options I can think of . Since fans always work off a relay you could use the trigger wire on relay instead of fan power wire .
Another option, many vehicle use a simple radiator or water temp switch to trigger fans, this also could be used .

With all ways just need to make sure it doesn't interfere with fan operation .

also, my LED would come on till i did grill block, and occasionally still. There's enough airflow to "windmill" the fan and generate enough power to light the LED

hmm, I didn't think of that, that might be another good reason not to wire into fan motor .

I bought a toggle switch with an LED in it. It had the resistor already built in. It was easy to mount the switch on the dash with a simple 1/2 hole and wire it from behind the glove box. Switch does not do anything just the LED built into the switch when then fan comes on. I don't have any windmilling.

I love the windmill effect with my incandescent bulb. It reminds me to slow down. :) It gets brighter when I'm going too fast and gets dimmer when behind a large truck. I can "see" wind too. "Fan on" is always much brighter, so there's no confusion. But I lose the windmill effect with the full block that's in now.

I did this on my car. Works great.

http://ecomodder.com/forum/showthrea...html#post93371