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  • microcontroller controlled. DIY HVAC retrofit??

    hello forum. i know, that stuff like that has been done before, using fusion brain or other microcontrollers, since i have seen some scattered posts..
    what i want to do, is make a HVAC system for my car, that will be controlled by an arduino, (prety much same as with fusion brain), and from there, i will contrroll the arduino via my carpc...
    the main problem is, my car does not have any AC at all.. it has an ancient, heated blower, that dosent even work so well.... so i am guessing, my best option would be to get rid of everything, and build a new system using other car parts... (vents, and everything)

    Could someone share some detialed info, on the varius parts needed,for a HVAC system??
    any previus expariance would be helpfull as well

    1)so far i have "Figured" , that i should use a servo, to controll, which vents get the air,
    2)controll the blower, via a PWM (i think so at least)

    but as for how to set the temperature, and what parts are needed for this job, i have no idea... :/
    edit: to heat the air, coolant from the engine is used?? this is true for newer cars as well??it seems prety primitive....
    Last edited by settra; 03-21-2014, 06:56 AM.

  • #2
    Primitive? How so? There is so much heat generated as a byproduct of internal combustion, why not use it? Essentially it is free heating.


    I'd suggest you establish what AC etc you are going to fit - the compressor, cores, console, fans, and integration into the heating, etc - at least then you know what hardware you need to control, and how.

    Comment


    • #3
      Originally posted by OldSpark View Post
      Primitive? How so? There is so much heat generated as a byproduct of internal combustion, why not use it? Essentially it is free heating.
      well yea , i agree on that. the only problem i can find, (and maybe it is so, because, that is what happens on my car) the engine coolant takes allot of time to heat up (certainly more than 10minutes), so the most days i use the car, i end up, just being cold ....

      so from what i hava found , all the magic, happens inside the HVAC "module assembly" or whatever. mine, either has space for the AC evaporator, or it dosent.... (my car model had versions with AC, so compressor and other parts, i could use from that).
      I think it works like that : (correct me if i am wrong) , 1) if you press the AC button (what does it ACTUALLY do? ) , the evaporator, (or AC radiator) gets cold.
      2) the air blower blows air, that passes from the evaporator, which makes the air Dry, and cold
      3) when you select how much heat you want, you actually open a valve, that lets coolant from the engine , to go through the heat core. so when the cold air passes from it, it becomes hot, and so you have your nice dry heat..

      so, in order to controll all that from the PC, you have to take control of:
      1)the motor blower (Easy)
      2)the AC button (i know it somehow turns on the air condition, but how?? the compressor is anyway always connected to the engine pulley...)
      3) use a servo, or a steper motor, to open or close, the valve that allows coolant to pass the heat core... is the thing that does that, called "actuator"??
      4) use another servo to control the air direction vents...
      3-4 and could be very strong servos, if the cars vantilation was designed with manual turning knobs...

      finally i was thinking: is there something like a "electric heated core", that you could use besides the "coolant" one, so you could get hot air, even if the car has just started?
      (in the microcontroller, this could be done by something like monitoring the engine temp, or use a raw "in the first 10minutes of run "

      Comment


      • #4
        i lost my answer . i ll write it again .

        my car has a heater that fits all vw vehicles in north europe. it is an expensive part ( around 600 euros) and it is below the vehicle. on the other hand you could use a silicon rubber heater.

        both of them ( silicon and the aux. heater that i mentioned befoore ) consumes enough amps.

        here you can get an idea
        Last edited by Happy_Feet; 03-22-2014, 05:23 AM.
        Vw Sharan 2007 1.9tdi || Exide 100Ah
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        • #5
          the aux heater, heats water?? i was thinking more of something ,that heats itself (like a coil or something) and then , the air passes through it...
          what are the silicon rubbers?

          Comment


          • #6
            in my car this heats the water so the engine would warm up in seconds. so the whole engine gets hot enough in less than 2minutes so the air coming from the engine is warm enough .

            the silicon rubber heater ( sorry for these guys -- αντισταση σιλικονης ) is a flexible resistance . i used that to build a egg hatching machine ( κλωσσομηχανη) .

            of course due to my poor knowledges these are what i understand. perhaps someone can explain better.
            Vw Sharan 2007 1.9tdi || Exide 100Ah
            Fuzzy 945gme + core duo T2400 + 2gb ddr 667 + pci nvidia 5500 256mb + kingston v300 60gb + hdd 2.5" 100gb 5400 + Sure Gps module
            Primary monitor 8" 800x600 || Secondary monitor 15.4" 1280x800
            Powered by M2 atx

            Comment


            • #7
              i see. but that way, the water heater, serves a whole other propuse

              well actually, what i am looking for, seems to actually be a thing : http://www.ebay.co.uk/itm/VW-AUDI-SK...item43c642a0d6

              serves the exact same propose with the heated core, but only difference, is it does it with electricity... but i am guessing the amps required for that thing to work, will be great, so its best to install both the coolant driven, and the electricity driven cores, IF (And that is a big IF) , there is enough space...
              that way, you could controll them like that :

              have a thermometer, that measures the temp, of the outgoing air.
              set a desired temperature, like 28 celcius.

              then, the microcontroller starts with, opening full the coolant valve. after some time, if the air is not hot enough, it start , applying voltage to the electric core.. when the temp gets more than the desired, it lowers the voltage of the electric core, and if its down to zero, it starts to close the valve...

              OF COURSE, you could go ahead and remove the coolant one all together... that might be ok, for a casual car, but pretty much, on all our cars, Amps are precious, so i dont know if its "fine" to spend them on heating... :P

              Comment


              • #8
                The AC switch engages an electric clutch that spins the compressor. It's a typical 'split' compressor fridge or aircon system - condensor in front of the radiator; evaporator in - or ducted into - the cabin.
                There are various interlocks - eg, economy settings; clutch disengages if the cabin fan is off and maybe during idle else idle speed increases with aircon on, etc.
                Just google car aircon and you should find suitable descriptions.


                As to the initial cold, heaters are usually taken from the head before the (mechanical) thermostat so warmth should be evident within 1 minute, maybe 2.
                In colder places, plug-in warmers are common. Usually OEM is a sump oil heater whereas DIY add ons comprise a short tube with heater that is inserted in the lower radiator hose. These are powered from domestic AC supplies and are usually timer set (ie, to come on maybe 60 minutes before driving).
                And there are also the auto systems - those that run the engine when cabin temperature drops below some limit. (They can scare the crap out of you when, er, communicating with your partner on the bonnet in some dark snow covered carpark.)

                Many people use 12V hairdryers in their demister ducts for faster defogging, tho aircons are far more effective at demisting and probably quicker.

                Electricity for long term heating simply isn't viable. Not only might a typical 2.4kW local AC heater NOT be anywhere near enough to warm a typical cabin, but that heater alone would require over 200 Amps @12V. Plus it would suck over 4HP from the engine.
                Compare that to water/coolant that can easily provide 10kW or more of heating without effecting engine power of fuel economy.

                Comment


                • #9
                  mmm. i didint realised that an electric heater core, would suck SO many amps (i though something about 20 - 30A). but if this is the case, then i guess i should find something smaller, to use only untill the water gets hotter......
                  a hair dryer is indeed a nice idea.. or something else that is small and gets hot :P

                  so appart from the AUX heater, i still will need two servos, to move the mechanical parts... (air direction, and the coolant valve) (my car dosent have the option for recirculated air), any idea what torque should i look for??

                  Comment


                  • #10
                    so, as i sed , my car does not have the option, to choose, between recycling the cabin air, or drawing from the outside....
                    i guess, for efficient heating, (And cooling), when the engine starts, it would make large difference, if it could just recycle the air from the cabin... correct??.. (Correct me if i am wrong).

                    so i was thinking this: my "air condition air intake" is in the engine compartment, just bellow the windshield... i could, make an assembly , that fits directly on it, and has two large tubes for incoming air.. the one will suck air from the enviroment. for the other, i will have to cut a hole, that gets inside the cabin. i will pass the tube though that whole, so that it sucks the air, somewhere near the passengers feet.... so i have two questions:
                    1) does this make any sense on doing, or am i talking crap? :P is there any point on doing it??
                    2) in order for it to work, i would have to install something like a "Flow direction electric valve"... or something.... any idea, what item could do that job??

                    i realize that this is a bit of topic, but with any luck, i might get some help on what to do

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                    • #11
                      I would recommend getting electric seat heaters, much cheaper and easier to install. They heat fast, and really warm your bones.

                      -Robert

                      Comment


                      • #12
                        Put in a block heater for faster warm up's (it keeps the coolant at a warmer temp overnight) you really don't want recycled air in colder weather, Most cars I see on the road with foggy windows have the recycling air switch on. in my truck its always on fresh air no foggy windows. Good luck SNO

                        Comment


                        • #13
                          After quickly reading this thread a few notes:

                          You didn't mention what car you have unless I missed it.

                          You don't need a heavy duty actuator/solenoid to replace the manual stuff. If you follow the cable that is hooked to the actual vent that is actuated and disconnect everything I suspect you will find the door moves easy. You want a linear actuator that has a feedback so you know how much it is open. You can fabricate brackets and push/pull rods to match up your actuator correctly. If it is a simple open and closed type setup you could likely use an old door lock actuator.

                          You need to understand how your system works and go from there. You likely have at least 3 different gates. One to control the outside or recycle air, one to control the temperature, one to control where the air goes. You should be able to replace all of the manual controls with solenoids/linear actuators. You need to look at a manual for your car to know for sure.

                          Beyond this when you look an an A/C system you need to realize it is a very complex system and if you can find a car with an AC system in it then it might be doable but it is a major undertaking to do yourself on your own. There may be some after market DIY add on units for older vehicles that make it simpler but otherwise you are biting into a project that would be hard to do with proper access to parts.

                          Good luck with this project. It is doable to replace manual controls with an automatic system like you are talking about but to go beyond that you are looking at possibly biting into a project you won't likely finish unless you can get all of the parts and documentation on how it all works out of another vehicle similar to yours.

                          Rodney

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                          • #14
                            Originally posted by redheadedrod View Post
                            After quickly reading this thread a few notes:


                            You need to understand how your system works and go from there. You likely have at least 3 different gates. One to control the outside or recycle air, one to control the temperature, one to control where the air goes. You should be able to replace all of the manual controls with solenoids/linear actuators. You need to look at a manual for your car to know for sure.


                            Rodney
                            its an audi 80, 1994.. and i must have at least 2 gates... (my car dosent have option for outside or recycle air).. well, i think i can get A/C parts. that fit my car rather cheap (from other versions of the same car), so as far as i can see, AC, just needs to be hooked, and it will "work", since i started the post i have searched allot on how those things work!

                            the fact that it dosent heat the cabin fast enough, is what concerns me... :/

                            SNO, i dont drive the car too often, nor on a regular basis that is why i look for something that does the job, as soon as i "Start" the car...
                            ( i am planing to add remote start, via phone some day, but this is still far).

                            maybe i could add one or two of those : http://www.ebay.co.uk/itm/Insulation...item2c736b870a

                            just before the "intake"... and have them work, with the OEM car heater...(ofc, i cant use the AC with them,to dry the air, because AC has to be before the heating matrix) but would 150watts, or 300watts, make any difference?

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                            • #15
                              Again, if you think a 15A load that puts out a bit more heat than a 150W bulb is worthwhile, go for it. But instead I'd advance your remote start - problem solved. Otherwise if parked in a garage or similar, why not an AC powered heater that you disconnect before driving off?


                              It surprises me that a 1994 vehicle does not have a fresh or recycle option, but no, I doubt that that would make much difference - except for fogged windows as SNO said.

                              But have you got the assembly you intend to fit yet? They are likely to have the all the venting necessary. Hotrods often use compact self-contained heaters with aircons (that's what I was considering fitting to my 45 years old vehicle when I used it for business).




                              PS - why not use halogen bulbs for heating instead of that ceramic heater? It's be a good use for half-blown H4 bulbs etc. Else use 12V 20W - 50W downlight halogens where you can;t touch the halogen bulb itslef. Much smaller and easier to mount than that heater, and only a 5% loss in heating efficiency (tho the possibility of a much higher temperature).
                              Or use an infrared bulb... Kill 2 birds with one stone.
                              Last edited by OldSpark; 03-31-2014, 04:55 PM. Reason: PS...

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