How to light hvac with LED's

This how-to will show you how to light up a 2g hvac (heater control assembly) with led's. I thought this looked so clean and so much better than stock that I had to do it! This idea is fully credited to azdave. I have azdave's permission to write this how-to.


All questions / comments should be left on this thread:
http://www.dsmtuners.com/forums/art...w-light-gauge-cluster-leds.html#post151318570

The stock brighness control has handled the LEDS just fine and our cars come with PWM brightness control which is perfect for dimming LEDs correctly.



Thanks to snowborder714 for photography / photo editing.


A. Disassembly
Warning: I had my brother and a friend helping me disassemble the hvac. It took all 3 of us to do certain parts, so beware trying this on your own.

1. Remove the hvac from your car:
http://www.dsmtuners.com/forums/articles-exterior-interior/282624-how-remove-hvac-unit.html

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2. Remove the 3 cables from the assembly. (I guess you could remove these cables from the hvac side during removal from the car, but it seemed easier at the time to trace the cable back and remove the other end of the cable from the car.) For the outer 2 cables, push the white clips together to slide the ring off of the peg. Then, use a screwdriver from the underside of the hvac to pop the metal retaining clip out. For the middle cable, pop the metal clip out from the hvac unit and slip the metal wire out of hole in the lever.

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3. Remove the single light bulb by turning it counterclockwise and pulling it out.

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4. Pull the knob off the lever.

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5. Now it's time to remove the outer 2 knobs. Turn the knobs all the way to one side so you can see a hole in the back of the hvac. You need to squeeze the black tabs inward as you pull the knob out from the front of the hvac. I used 2 small screwdrivers to squeeze the tabs in.

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6. Remove the black part from the back of the center knob using a small screwdriver. Be careful, I accidentally broke this piece and will repair it with superglue.

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7. Remove the next piece in the switch by pulling it out.

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8. Remove the c clip from the switch using a screwdriver. Now you can pull the knob out the front.

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9. Now you're ready to pop the black part away from the white part. Using a small screwdriver, pop off the white tabs holding the black part on and separate them.

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10. Remove the a/c switch by squeezing in the tabs and pulling it forward from the hvac.

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B. Lights

1. Cut the light off of the harness and strip the ends.

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2. Pop the pins out of the connector by using a small screwdriver to press the tabs in.

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3. Cut a strip of 45 lights and cut the insulation off the ends to reveal the end terminals. (Note: Fewer lights could be used if several strips were used instead of one big strip. I chose to use one big strip because it was much easier.)

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4. Solder the wires onto the led strip.

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5. Stuff the leds inside the case. I used carpet tape on the outside edge of the strip to hold it in place. Note where I used a piece of insulation as a spacer to ensure the lights stayed directly under the parts on the hvac where the light shines through. Route the wires through the hole. Put the pins on the wires back in the connector.

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6. Disassemble the a/c switch by using a screwdriver to press in the small tabs on the side and sliding the switch out of the case.

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7. Unscrew the light bulb.

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8. Cut a strip of 3 leds and take off all of the insulation. Cut one light off from the other two and solder wire onto both terminals on the single light bulb. Place the single light bulb inside the hole where the old light bulb used to be, facing forward. Solder the negative wire from the bulb to the negative terminal on the circuit board.

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9. Cut another piece of wire and solder it to the positive terminal on the circuit board. Tape everything up well.

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10. Place ONLY the a/c switch CASE into the hvac assembly.

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11. Cut a hole into the a/c switch case as shown. Now, place the a/c switch back into the case and route the two wires through the hole.

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12. Solder the strip of two lights you cut off before back onto the wires. (Note: These lights are wired in "threes", so you can not just use one light, you must have all three or the lights will burn out. I'm sure there is a better/cleaner way to do this, but this way worked for me.)

Good suggestion from VelocitàPaola:

First, for the A/C switch light, I suggest simply wiring a 220ohm or 330 ohm resistor in series with a single LED. That way you can eliminate using the other two unnecessary LED's. There's really no difference between using the 220 or 330ohm resistors. In fact, both are slightly overkill, but those are very common resistor values that are easy to find. I believe about 120ohms would be ideal (depending on the specific LED), but the extra resistance added from 220 or 330ohm resistors is imperceptible and a good safety net.

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13. Tape everything up real good.

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14. Put everything back together the reverse way you took it off.

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