The only things electrical are the blower motor and the a/c clutch.
All else is vacuum and cable. The reason replacing with electrical motors/solenoid was brought up is because you might be able to replace the vacuum motors with them (find a way to mount similarly) and you would have pretty close to the same physical footprint AT the doors. Behind the HVAC control you'd be a little ahead.
Thinking about it - why not use the same as what you are replacing the temp cable with? The vacuum motors are just moving arms in the same way as the temp cable. All comes down to mounting them in the right orientation.

 

If it were me, I'd map all of the different positions and vacuum signals and see how many solenoids I would need. May have to find some multiport ones. Should pretty well be all that's needed to convert the controls to electric, best I can imagine. I figure you'd have to run those through relays.

 

Why not even simpler and keep the existing vacuum valve (the multi port one attached to the HVAC controls) and use something like the linear actuator (I don't know what all options are out there) to move it. So don't reinvent the wheel at all but just change who/what moves the levers.

 

That seems like a rough way to do it. Might be even easier to replace the vacuum motors with electric actuators, kind of like the idea of keeping the vacuum stuff myself.

 

Rough? How so? It would require no modification at the doors and would only require one add-on device to move the existing slider inside the vacuum switch.

 

Are you keeping the controls in the same place?

 

Yeah, I guess we are likely picturing different things. I was thinking it might make sense to keep the core HVAC bracket but replace the front plate with the digital display. Then keep the vacuum valve and temp cable attached in the same locations while finding a way to mount the new arduino controlled actuators/solenoids so that they can just 'tie in' and take over.

 

Yeah, I was figuring the original controls would be removed. I guess you could chop it down, and mount it behind the dash somewhere. Seems like it'd be more reliable adding in something manufactured to do that job. Best I can remember there are 4 outputs. Haven't found and multi output switches though. Looks like you could use 4 of the solenoids. Be a little pricey. What about the visual interface? Would you keep the look similar to the factory controls or use something out of a newer vehicle? My wife's Jeep is alright. Interface is good, but the functionality isn't great. It's got sliders and I do like that part of it.

What I'd like, if you were going whole hog. Is to change the venting up a little bit and have controls to cut each vent on and off separately. Then I'd want all of the vents indicated on the touch screen, visually. Then you could touch them to turn them on and off, or also use a slider to control how much flow is coming out of each vent.

 

The vacuum diagram is in post 2

 

I can see it now a 3K HVAC control system in a $500 truck

So what is the reason for doing this?
Just to have a touch screen to work the HVAC?
Hey its your truck do as you wish as they say and I will be following if you do this.
Dave ----

 

My overinflated opinion:

Keep the existing spring-loaded vacuum actuators, and plumb them to a common supply. On the line to each actuator, add an electrically controlled spring-loaded SPDT solenoid. Plumb the actuator so it's either connected to vacuum or vented, an either/or arrangement. You can't use an on/off solenoid because this would trap the vacuum in the line when switched off, and the actuator would never relax unless it had a leak.

Follow the same vacuum logic as original. With the OEM arrangement, a loss of vacuum causes all of the doors to relax to the defrost position. This is for safety, so you can always see. Arrange the solenoid control the same way, so any loss of electric power still keeps the windshield clear.

You could mount the solenoids anywhere convenient, even under the hood. I'd keep the original vacuum actuators as they are already spring-loaded to the correct default position. You'd skip having to make electric actuators fit in very cramped quarters.

For the hot/cold control, remove the control cable and secure the blend door in the full hot position. The idea is you want all airflow to pass through the heater core at all times. To control the heat output, install a spring-loaded electric coolant control valve. Most newer cars are like this. A variable PWM signal from the controller regulates the flow of hot coolant through the heater core. Want cold air? Shut off the coolant flow. Want full heat? Send full coolant flow. Want something in the middle? Tweak the PWM signal for partial coolant flow. Once again, for safety, plumb the valve so a loss of power equals full coolant flow.

 

Having had the blend door actuator **** the bed in a never vehicle. Well, more like dealer smashed it during second airbag recall(on number 3 now). If it fails you can manually switch it under the hood. Did that a couple of seasons until I found the right part. I hadn't considered the solenoids holding pressure. If it were me I'd mount them under the dash. Less wires and vacuum lines to run.

 

That's why the EGR solenoids under the hood have a foam filter. When you relieve a vacuum system, you actually have to let air in. Theory is the same as a pressure system, only being vacuum it's backwards.