Ok I want to change my climate control lights to Blue LED's but I dont want to have to take the climate control out of my dash to do this. Is there any way to take off the cover to the control system while its in the dash? One more thing....What size of a resistor do I need to make a 4V Blue LED work on a 12V system? I hope someone can help me!!

No, you have to take it out.

~snap

Calculating an LED resistor value connected in series:

The resistor value, R is given by:

R = (Vs - Vl) / I

Vs = supply voltage (12V)
Vl = LED voltage (4V in your case)
I = LED current (e.g. 20mA), this must be less than the maximum permitted

If the calculated value is not available choose the nearest standard resistor value which is greater, so that the current will be a little less than you chose. In fact you may wish to choose a greater resistor value to reduce the current (to increase battery life for example) but this will make the LED less bright.

For example
If the supply voltage Vs = 12V, and you have an LED (Vl = 4V), requiring a current I = 20mA = 0.020A,
R = (12V - 4V) / 0.02A = 400, so choose 470 (the nearest standard value which is greater).

That's right... to remove leds you need to open climate control like this:



so your panel will look like this:



you don't have a chance to do that without removing panel out.