HVAC Control


I have integrated an Ipad into my C5 Corvette (out of boredom) and due to lack of space on the dash, I'm going to have to relocate my climate control cluster.

I want to use an Arduino with a series of servos to either wirelessly or by cable, control the hvac cluster with some kind of interface on the Ipad. I'm new to Arduino, but I am a fast learner and would like to take on this project. If you guys have any suggestions, I'd love to hear them!


Dan Greenville, SC

After more thought, I'm conidering building a small container to house the factory controls for the climate control and arranging servos to be able to push the buttons on the panel. If I remove the hvac clusters faceplate, the small buttons on the board are easy to push, so I'm thinking micro servos should be able to do the job. I'm also wondering if I can use the servos to push one button turning clockwise, and push another button counterclockwise. I will need 5 servos set up with plungers to push the buttons in this manner, and 2 servos that can turn two dial knobs.

I know this may sound like an uncanny project, but I don't know any other way to do it.

I'm assuming I can possibly do this with an Arduino Uno and some time to learn the code. If anyone can point me in a direction to get started and what I may need to wirelessly communicate with the setup eventually with my Ipad, I would appreciate the help.

I'm not sure if anyone else has successfully got their Ipad to control their vehicles climate control, so maybe this can be the one of the first!

Thanks in advance!

Hi, The buttons should work OK.. But the rotary controls on cars (Pardon me for calling a Corvette just a 'car') are usually hard to rotate. Maybe to keep them secure from vibration.

How easy are yours to rotate? Servos are rated as Torque , usually in KG/cm. For example, look at this servo and click on the photo to see the torque ratings: http://goo.gl/sl2gA

Thanks for replying!

The dials are pretty easy to turn. I was into rc planes and helis back in the day, and I'd say a standard servo would work fine on the dials. One of the dials (driver's side temp dial) does not turn 360 degrees, so some kind of code will have to be written for +/- limits, but the other dial (passenger side temp) can be turned inifinitely either way. It may not hurt to buy a couple of higher torque servos for the dials just to be safe.

I was browsing around today and found an app for the Ipad called "Ardumote HD"... I'm reading about it right now, but I'm just trying to find a way to communicate with the Arduino solely with the Ipad. I mean if initial programming with a pc is required, then no worries, but I want to be able to cut the cords and pull the vette out of the garage with full control of the hvac.

I'm also sketching up some kind of "box" to mount the hvac control and servos with some push-rods to interact. The dial servos may need some type of gear set up.

I think it would be kind of neat to design an interface on the Ipad that looks like the factory controls, but that can come later.

Is there a way to add the extra needed power for 7 servos via dc?


I will need 5 servos set up with plungers to push the buttons in this manner, and 2 servos that can turn two dial knobs.

You may only need one or two servos. Servos don’t usually go 360, so depending on how the passenger’s control works, you might just need a geared (slow) DC motor for that one. But if you don’t use a servo, you’ll need some feedback to know what the setting is… If there’s a thermostat, you’ll need to read that “feedback” too.

For the pushbusttons, a solenoid ([u]example[/u]) is more appropriate (and simpler to drive) than a servo.

I never thought of solenoids... I need to rip apart my hvac cluster so you guys can see what I'm talking about. There's 10 buttons total and two knobs... I considered the servos because I can use one direction for one button and the opposite direction for another button... I'm just assuming that I would need 10 solenoids compared to the 5 servos to handle the buttons. And that is totally fine, but would I need to step up the the mega instead of the uno?

Forgive my noobness, but I can't find a definite answer... I'm heading to Radio Shack to buy my first Arduino today and take my first steps at figuring out this project.

I'm just a little confused on which board I need to get if I want to have total control of seven servos (or an alternative of ten solenoids along with two servos)...

If the Uno can handle this project, I'd rather save the money and overkill of using a Mega.

Thanks in advance!

Hi guys! I'm still brainstroming over this project... I bought my Arduino Uno and have completed the basics... leds, controlling servos, buttons, sensors, etc... I am waiting on my wifi shield now and still debating on what to use as an interface on the Ipad. NetIO looks promissing.

The question I have now is, do I really need servos to control the factory hvac panel? When the front panel is disassembled, the buttons on the front are very similar to the small buttons included with an Arduino startup kit. I'm assuming that all they do is complete a circuit... could I solder leads to these switches and just complete the circuits using outputs on the Arduino? I know it can be more complicated than that... knowing voltages, etc. On the switches.

I'll stick with my servo idea for now.

I would use relays control all the buttons, and for the climate control knobs i would use linear servos. The ipad sounds good but you need to design an app for it not so easy task or you could use a touch pad for the arduino most of the code is online.