Need guidance on repurposing HVAC controls.

Projects General Guidance
1

Hello, I need some guidance help. I have played with Arduino and electronics before, but consider me an absolute novice.
I am wanting to replace the archaic controls in my car (Cable operated hot water valve, vacuum line operated feet/window/recirculation buttons) to some slightly more modern controls. Both for looks, functionality and because the mechanical valve is absolute junk and there is no solution other than using a garden hose valve.

  1. Inputs

    After removing the original pcb, I am left with 3 potentiometers and 2 push buttons.
    a) The buttons I'll salvage by cutting the original pcb with a dremel like shown here, so they maintain their mechanical functionality, and solder wires onto the pins on the pcb.
    b) I'm having some trouble figuring out the potentiometers. The left one seems like a normal potentiometer, 7 positions and 3 wires. The other two leave me perplex, lots of pin outs and positions. Here is a detailed picture. The only way I can think this is working is that one pin is a ground and the others are acting as buttons. Which would mean all these pins going into the Arduino I am guessing, which I'm not sure even a mega has enough inputs, and anyhow I wanted to use an Uno if possible, if not smaller. Any way around this? Any interface? I am aware that swapping in standard potentiometers would not be a big issue, but I'd like to maintain the factory... "clicks into place" on the correct positions.
    c) A temperature sensor (for automatic climate purposes, which I'll worry about once manual is working).

  2. Outputs
    a) Small 5v air solenoids to replace the original buttons for feet/window/recirculation which just closed a vacuum line, cheap from China.
    b) I'd like to bypass the original wiring and figure out something to control the 12v blower motor directly from the arduino allowing me the 5 speeds (original has 4). I'm guessing I should just read up on controlling motors for this.
    c) The water valve is a real issue. I can find plenty open/closed solenoids on ebay, but nothing that can be adjusted in degrees, especially by an arduino, any thoughts? Water is roughly 90 degrees celsius, and the tube isn't bigger than 1/1.5 cm if memory serves.

I'd appreciate as much input as possible on all points, especially 1.b and 2.c, but validation on the others as well if possible.

Thank you in advance.

2

I think you may have screwed yourself by cutting the ribbon cables.

A potentiometer does not have step positions. A rotary switch does. The two other controls are rotary switchs with encoded output. The left one is 8 bits and the right one is 16 bits. Both sent bit patterns, 0-7 or 0-15, to the actual control unit.

I am not sure if any standard Arduino has enough IO pins to be able to even read the switch settings from your control panel. Perhaps someone else can offer a solution, but I think you have some electronic engineering ahead of you.

Paul

3

Paul_KD7HB:
I think you may have screwed yourself by cutting the ribbon cables.

A potentiometer does not have step positions. A rotary switch does. The two other controls are rotary switchs with encoded output. The left one is 8 bits and the right one is 16 bits. Both sent bit patterns, 0-7 or 0-15, to the actual control unit.

I am not sure if any standard Arduino has enough IO pins to be able to even read the switch settings from your control panel. Perhaps someone else can offer a solution, but I think you have some electronic engineering ahead of you.

Paul

Well, crap. Should have know Volvo knew what they were doing even in 1994 far more than what I do in 2017.