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Help with a big HVAC project.

Posted: Fri Jan 03, 2025 11:08 am
by SsCoobyDoO
I have a lotus esprit but I am also parting out and scrapping a 2004 audi A6. They were going to give me 250$ for the whole car... Yeah right. It just has some bent valves it even has the parts to repair ir but I decided to do a part out.

I got ahold of the climate head. I thought about intergrating it into the lotus or my wifes MK4 golf. The problem is I am not an electronics wizzard. The same night I got ahold of an old printer. IT had a gearbox with a dc motor and an encoder wheel which is perfect for the issue I am having with the lotus. The mechanical system is just too stiff to use anything other than the factory knob. I have a bunch of rotary encoders and the LED displays from the audi.

I was thinking about using an arduino. HAving the rotary encoders feed data to the arduino the arduino sending signal to the motors to control fan speed. flap angle and hot/ cold valve operation. Then the opticoder on this gearbox can tell motor posistion. I know enough to hook the encoders to the arduino but I do not know how to make the arduino take the data from the opticoders and use it for posistion finding. Aka I want to make the motor behave like it did in the printer. Stepping.


I also do not feel confident enought to write the code. someone stick me in the right direction I have spent 10 hours reschearching.

Re: Help with a big HVAC project.

Posted: Fri Jan 03, 2025 2:03 pm
by traysmell
Lol I was pretty sure no one was going to touch this even with the tippy tip of their unicorn horn. So I have made a bit of progress. I have absoloutley demolished the interior of the A6. I am nearing the point where I can harvest the whole loom along with the HVAC unit. The only problem now is there is a subframe in my way. So that said I am switching gears with the project and I am going to see how hard it would be to wire in the head unit and the motors using the original loom. I should just need an arduino to act as the brain.... OR I might get lucky and Ill be able to just plug in the control unit but I aint that big of a dreamer.

Re: Help with a big HVAC project.

Posted: Fri Jan 03, 2025 2:07 pm
by hamemont
I’ve done some small stuff with Arduino before, like controlling lights and fans, but getting stepper motors to work with position tracking is definitely a step up.
I’ve also learned the hard way that having a good wiring diagram is a lifesaver. If you can’t track down a pinout for the Audi system, maybe hit up a local Repair Near Me shop. Sometimes they’ve got the tools or know-how to help you figure out those tricky connections.