Fan switch mod with bi-color LED

I mounted the switch and the LED under the cigarette lighter, it looks pretty good there.

Here are a few things about LEDs if you don't know much about them.

Remember, and LED is a lot like a light bulb, EXCEPT they will only work when they are connected properly. One pin must be connected to ground, and one must be connected to a positive voltage. If you get the pins backwards, it won't work.

  If you connect an LED directly to the 12 volts coming from your car, it will burn up. To prevent this, you need a resistor in series with the LED. To calculate the value of the needed resistor, divide 12 by the max
current (amps) listed on the LED package, that will give you the resistor value you need for that specific LED. You will probably need about an 800 ohm resistor, since most LEDs use about 15 milliamps.

12 volts / .015 amps = 800 ohms
This is the calculation you would do if the LED you bought was rated 15 ma. It tells you that you need an 800 ohm resistor in series with the LED.

The cathode is the negative leg of a diode, the anode is the positive lead. The anode(s) and cathode should be indicated on the LED package. The bi-color LEDs will have two anodes, and one cathode. One anode will
is for the green filament, and the other is for the red.

If you want to send me an e-mail asking if you have the right values before you hook it up, that is fine. I never made it to Radio Shack to check out specific catalog numbers.

You can get holders for the LEDs if you want to put them under the cigarette lighter, I got some small chrome ones and it looks like something from the factory, really nice.

If you aren't really sure you have the circuit just right, try it out before you solder anything up or drill any holes.

You can get the power from the back of the cigarette lighter, I can't remember which one is positive though, you'll have to check.

I connected the power to for the LEDs to a fuse (instead of the cig lighter) that only has power when the car is on, or after the car has been on until the doors are open. You might want to do that so it doesn't run your battery down. As long as the fans aren't running, the battery will last a long time. This way it will turn
the LEDs off when the power goes off. Even with the LEDs on (~40mA or less) , the battery should last for a couple of weeks, but I did it just in case. Just use a voltage checker or one of the LEDs with a resistor
to find a fuse that goes of when the power is turned off (when the radio goes off after the car is turned off). Then you can buy a "fuse power tap" that fits in the socket behind the fuse and connects to your power
wire. You could also make your own just using some thin piece of metal or something behind the fuse and connected to your power wire.

Make sure you don't leave the fans on for more than maybe five minutes if the car isn't running, they take a lot of power and will drain your battery pretty quick.

Below is a picture of the switches and lights in my car, I have a switch for the fans and one for my amp. The picture is pretty crapy, but maybe you can get a general idea of where I put mine. Also pictured are a bi-colored LED and a DPDT switch. The LED pictured does not have a socket, you can get sockets at Radio Shack, where you'll probably get the switch and LEDs. Under the pictures is the schematic.

I think that is about it, good luck!  
E-mail SteveR