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Thread: microcontroller controlled. DIY HVAC retrofit??

  1. #11
    Maximum Bitrate rray's Avatar
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    I would recommend getting electric seat heaters, much cheaper and easier to install. They heat fast, and really warm your bones.

    -Robert

  2. #12
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    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

  3. #13
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    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

  4. #14
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    Quote 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?

  5. #15
    Raw Wave
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    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 at 04:55 PM. Reason: PS...

  6. #16
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    my 2cv had the heating system ( if it can called a system ) wrapped around exhausta pipes. it was very fast ( as the pipes close to the engine can go up to 300-600 celcius and costed nothing to the car's behavior.

    you should look at this too as the only thing that you are going to need is an aluminium flexible tube and a fan for drivinf the flow where you want.....!

  7. #17
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    OLd_spark : i dont really think that 300watt will do much of a difference. especially if OEMs fit, 2000watt or more... but so far, seems like the only valiable solution... as for the light bubls: i am arledy going paranoid, about being afraid that the tpc heaters will make the car catch fire... imagine having a a light bulb, that works by extreme heat :P also, those ptc elements, are supposed to be designed for that kind of job... the air passes inside them, so they must have better heat transfer....

    IN any case, i think that controlling them with just a relay, open or closed, will be enough...especially since, after the car is on for 10 minutes, there will be no need for them to be "on". no need for pwm!

    Happy_feet. i have seen this. especially in older cars that did not had a cooling system at all... but it would require too much work, not done by me (e mechanic or something), to make the vents go around the exhaust.... + it would require a system, that cuts off the airflow from those vents, when the AC is on... (imagine having too cooll down all that hot air :P )

    btw thanks for the great replies everyone!

  8. #18
    Raw Wave
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    I agree that a few hundred Watts won't do much - except to flatten your battery.
    But you linked those ceramic heaters which need mounting and a fan. Downlight halogens may be easier to mount and small PC fans are probably enough to dissipate heat.


    As I said, I suggest you advance your remote start, else get an off the shelf system. You can replace that else or add your phone interface later. IMO that will be a lot simpler and safer (battery wise) - and maybe cheaper - than electric etc heaters. Plus you won't have to wait as long till you can thrash the engine.
    Your smart interface could detect humidity of fogging and run the aircon so it's warm & demisted by the time you enter the car.

  9. #19
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    Chances are that you have recycle and external air but it runs in parallel with something else or it may be an option you are not aware of. You may find that the defroster setting uses outside air, the bottom feet option uses inside air and the vents facing you uses outside air. Or some other combination. (Defroster with anything else would still be outside air)

    If you are worried about the interior of your vehicle not getting warm enough I would suggest the following 4 things...

    After Market seat heater. My truck has one and now I don't want a vehicle without it... OMG does that warm you up...

    Block heater. The AC heater mentioned elsewhere. This will get your car up to temp fast and will actually save you a little bit of gas but you have to remember to unplug before you drive away...

    Car start... Gets car up and running and heats the inside of your vehicle. Does burn more gas though. But if used with block heater your car could get toasty by the time you get out to it. I have one on my truck and if I let it run the full 25 minutes my truck will be toasty even at 5F or below.

    Aftermarket heater in your vehicle... I have had one of those wierd clip on 12volt ceramic heaters in my car before and they do work... But you really want to aim them at you... And you probably don't want to run them without you being in the car or with it off. You could permanently mount one and have it come on when the car is running.

    Beyond all of that a car as "new" as '94 should throw the heat out pretty well. Make sure your heater core is not plugged up and make sure your thermostat is working properly. You can run a higher temp thermostat if one comes for your car but you would want to put a cooler one back in in the summer time. Depending on your car this could be a very quick installation. (In all of my vehicles it has been in an easy to find location and was 2 bolts.. Took all of 5 minutes to change out on a COLD car...)

    Another trick is to block some of the radiator. In the winter time some cars cooling system will work too well and blocking off some of the radiator works well. A lot of trucks will put an aftermarket made wind block on the front of their grill to block all of the air coming from the front and they have snaps or other means to partially open for towing. You may find you get enough air movement from under the car to cool the engine sufficiently. You will want to experiment to find your "sweet spot" but realize that you need to remove this wind block when the temps rise. You could just stick a piece of card board in front of your radiator to partially block some of it as well. Again experiment to see how much you can cover. This is a common thing in my area because we get temps in the winter time in the single digits F (-C).

  10. #20
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    nice info
    well, i havent taken appart anything yet, so indeed , i cant be 100% what my car does have , and dosen't have ... the truth is, i hadent thought, that maybe the "Defrost" setting, has diferent air intake than others... my control looks like this :
    Name:  2w4e792.jpg
Views: 48
Size:  54.1 KB.. the heat, and the level, have electronic contectors, but the airflow direction, has just one wire, which i suppose turns something inside the heater assembly..

    anyway, this is why i do so much search before starting so i can know what to look for! thanks again!

    also :
    Beyond all of that a car as "new" as '94 should throw the heat out pretty well. Make sure your heater core is not plugged up and make sure your thermostat is working properly. You can run a higher temp thermostat if one comes for your car but you would want to put a cooler one back in in the summer time.
    P.S : audi 80 i supposed to have one of the hardest to replace thermostats ever BUT. i drive this car for like 6 years. before that, it belonged to my father, who had managed to BURN it 3-4 times... he always forgot to fill up the coolant, and didint cared when the warning lights where shining .... :P the point is, he had replaced the thermostat, with one that comes on, EARLIER than the OEM... could this play a part on why the heater is not so efficient??

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