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A/C Control Electrical,Vacuum, and Mechanical

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  • A/C Control Electrical,Vacuum, and Mechanical

    I've been working this project for a couple of months now and wanted to post some of the progress to get feedback.(Hopefully Positive)

    In order to mount the screen I used from an older laptop I needed to make room in the center dash area. I had to remove the A/C controls that were once located in the bottom 3"-4" of what is now the screen. The screen is 13.3" with an easyscreen resistive touch panel. The laptop was then cut in half at the base to fit it in the console and still allow access to the CD/DVD. I have divided my project into three phases to help explain the method in which I choose what is important at any given time.

    Phase 1 - Develop a system, gather hardware, make a plan, and prove that it can be done.

    Phase2 - Make it work reliably (Easier said than done has been my experience)

    Phase 3 - Make it pretty.

    As of right now I am in phase 1.5 on all of the systems I plan to integrate.

    The first and easiest part of the A/C system was the fan speed. Since this is all done electrically I used 30 amp relays with the coils powered from the single board computer.

    The next task was to develop a system to control the vacuum actuators. I was fortunate enough to run across some micro SOVs at a laboratory equipment sale. They are manufactured by Clippard The type I am using is the EC-3M series on a 6 hole mounting bar. The price for new 12V solenoids is $20.90 ea., the manifold for 6 is $13.00 and misc. fittings ~$10. The valves I have are 24 Volt (The EC-3M is available in 12V) so I had to use power from my laptop P/S (19V). I used a relay box to isolate the SBC from the 19 Volt power. I then hooked the engine vacuum to the manifold common and the 5 color coded hoses to each valve. To determine the correct sequence for the vents I blew air through the vacuum selector valve and determined which hoses were used in each vent configuration.

    The last control was the Hot/Cold selector. This is a large flap that swings between the A/C Condenser and the heater core. This flap was controlled by a cable driven knob. I decided to use a servo to control this function. RC servos are controlled by A PWM signal. This signal has a pulse that repeats every 20 - 50 ms. The time of the on pulse dictates the position of the servo. The two main ways I found to control the position was by using a serial port interface or a IC timer circuit. I needed to use the timer cicuit because I am using my SBC to control the position. (Analog 10Volt Out Channel) Instead of building a custom circuit I found an RC Servo tester on Ebay and jumpered my analog signal across the fixed resistor. The first pass at servo mounting hardware was horrible.(No pictures, Thankfully) It did however prove that the servo idea would work. I then had a custom mount machined from aluminum. The black assembly at the end of the cable is what actually turns the flap.

    To help speed the development stage of the control system I have been using a program from This package installs a stand-alone kernel on the SBC and provides a graphic interface on my Win machine. This program is very quick and easy to integrate. The down side is that it does not utilize the full capability of the Z-World BL2100 SBC. Sometime in Phase 2 I plan to use Dynamic C (embedded language included with 2100) to make a better application for pc based car control. The pictures I took are not very good. I was going to take better pics but ran into a hardware problem on my SBC. Hope to have that fixed soon! I hate to operate in manual mode.

    I will continue to make updates as significant progress occurs.[LEFT]
    Car PC - If you have to ask why, you'll never understand.

  • #2
    Frickin amazing!!!!!

    Good job man, you have my respect!

    Single Member of the "1000 Post and No MP3 Car" Club
    2000 Cavalier Z24 [###-------] Only 30% Done ... Still


    • #3
      I have seen his (Z28Control) AC unit in action.... It is truly amazing... Still has a way to go on the rest, but man the potential of this combination with a SBC is awsome!!


      • #4
        More texans, good to see. I was interested in doing something similiar, thanks for the inspiration :}


        • #5
          thanks man. I have an 86 Z28 and wanted to do the same thing but didnt know where to start. Now I do. Thanks again.


          • #6
            wow excellent work
            92 Taurus SHO - Daily driver - Epia M10000 80GB 512mb 7" touchscreen, Opus PSU etc

            93 Black SHO - 30mpg cruiser

            90 Silver SHO - 419whp fun/project car, CarPC to come (for tuning)


            • #7
              I have a '93 MR2. The USDM setup has a cable-controlled temperature valve. The modes are controlled by a couple of stepper motors. The fan is controlled by a series of varying resistors, each connected to its respective fan speed selection.

              Can someone help me with what I need to obtain to make this project work? I know that I will need a servo to control the cable-controlled temperature valve. Can someone give me a brief explanation on stepper motors and resistors? I am not sure what the best way to go about controling these with the carputer would be and any help would be much appreciated. I am not really looking for a fully automatic setup as my car is really only a 3 seasons car and the climate control is not in regular use like many other cars. I like to take the t-tops off I am just looking for a simple yet effective control of the pre-existing controls only through the carputer.

              Thanks Guys



              • #8
                Can anyone please help? I am fairly new and am still trying to fiigure things out and there isn't enough information available on the searches.


                • #9
                  Hey i was wondering if there was any more progress in this?

                  you have me really curious ... i'd love to do this and i have the same car as u(well close .. i have a 99z28)
                  1999 Camaro z28
                  -- Computer installed :) Phase 1
                  -- z28 302hp dynoed :( WAHH!!!!


                  • #10
                    have always wanted to do that, but haven't ever started due to fear of not being able to figure everything out (esp. the vacuum tubes). im impressed, and jealous of your knowledge! where did you learn all the necessary info to do this? does your job somehow address any of these issues? Ryan


                    • #11
                      Jumpin criminey!! Dude, that's about as badass as it gets! (Also the epitome of geek). I've been looking into possible solutions for climate controls as well, but since I have yet to get a car that's worth making such drastic permanent changes to, I wasn't convinced vacuum-controlled systems were possible to control digitally.

                      I have been (quite ecstatically) proven wrong! Good job so far, can't wait to see how it's coming along!
                      The ALEXIS Project
                      Color Coding :


                      • #12
                        Negative Progress

                        Since I started this thread I've had some set backs that have left me at negative progress as of this post. I was already using outdated equipment when I set out on this endeavor. It was a AMD K6-2 500mhz laptop that I had cut in half to fit in my dash. This caused all kinds of multitasking issues due to the slow processor. I was also using the 13.3 screen from the laptop as a display. This caused two problems, it was not bright enough to be useful in the daylight and it had a very delicate ribbon cable that I tore twice. After the second cable I decided that I had endured enough pain. I then decided to shelf the carputer project for a little while. I was also having problems with the single board computer. The software package I used made it easy to program but a nightmare to use. I needed a break! I then started using a portable MP3 player for a while. After about 3 weeks I was ready to start over. I purchased a micro-ATX mobo with a 2.4ghz AMD XP processor and a Lilliput touch screen. This made my life a lot easier. I then shifted my focus to modifying the PCM using LT1 edit. I started with small changes like fan temps, redline, top speed adjustments because I had no way of knowing what effect fuel and spark changes would have. I have recently purchased a GTECH performance meter to provide that feedback. Of course new toys get priority. Now that the new has worn off I plan to get back to the climate control interface. I have decided to do an article to share the information I have found as a result of trying to interface the car with the carputer. My search was always conducted with cost in mind. I also plan to share ideas on how I would have done it if I had a lot of money to spend on this project. I hope to use the money I saved to convert my engine to a 383 stroker with the lt4 heads and intake. I will try to get the article and my website ready to view by March 18th.
                        Car PC - If you have to ask why, you'll never understand.


                        • #13
                          Cool Project. I would like to see it finished.
                          -Jesus- King of Kings Lord of Lords


                          • #14
                            Hey, just wondering if we can get an update on how the progress is coming with the new hardware? I have a 94 Camaro, still in planning stages for the carPC and definitely would like to know how to do fully operate my HVAC off of my computer before I go about cutting my dash apart. Thanks!
                            CarPC v3 - 6/4/2008 - Project Showoff Thread
                            CarPC v2 - Project Showoff Thread
                            Michigan FBody Association - Administrator and Owner


                            • #15
                              Another raise from the dead.

                              Z28control, if you are still on this board can you update the pics, I really want to see them. If you've made progress on the setup, give us an update.

                              1999 Black Pontiac Trans Am
                              CarPC's in F-bodies
                              How To Relocate Climate Controls on the 97-02 F-body Cars
                              (AMD Sempron 3000+, Opus 150)
                              Car PC system is out, Alpine system is in.