• AspieEgg@lemmy.blahaj.zone
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    3 days ago

    When I press the defrost button in my car, it turns both the heat and AC on at the same time. I assume this is to remove water from the air with the AC, then warm up the air increasing its capacity to hold water with the heat.

    • marretics@discuss.tchncs.de
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      2 days ago

      Your assumption is correct Also your car automatically calculates the condensation point and keeps the temperature and air moisture low enough not to cause any fogging on your windshield. Source: I’ve been programming AC unit controls for cars for the last 10 years

      • MML@sh.itjust.works
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        2 days ago

        They only do this with the automatic controls not basic knobs right? Apparently affected what filter I had to get.

        • marretics@discuss.tchncs.de
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          2 days ago

          Yes of course. The old school manual controls are usually mechanically connected directly to the flaps, so you cannot have any automated handling there

          • MML@sh.itjust.works
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            2 days ago

            Thanks, just didn’t know how far we strayed, my first car had separate keys, apparently the new one can detect air quality and automatically close, new is also relative.

      • ayyy@sh.itjust.works
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        2 days ago

        How upset do you get when your buddy disables auto and proceeds to slam back and forth between full heat and full ac while claiming their shitty dial dj set is somehow waaaaay better than the computer?

    • nova@lemmy.wtf
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      2 days ago

      in a lot of newer cars they can actually use the A/C to heat and cool the car, rather than using excess engine heat or an electric heater which is especially helpful when it’s cold and you’ve only just started the engine!

      • boonhet@sopuli.xyz
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        2 days ago

        I assume you mean EVs with heat pumps? I don’t know of any ICE vehicles that do this, seems inefficient to waste mechanical or electrical energy when you have perfectly good waste heat to use upon reaching operating temperature (though you may need to use an aux heater before reaching that, particularly on diesels)

        • Natanael@infosec.pub
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          1 day ago

          Lots of new EVs have heat pumps, in cold climates they need it because the car doesn’t generate enough heat just from running.

        • FordBeeblebrox@lemmy.world
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          2 days ago

          It’s also an emergency safety heat bleed if your engine is overheating, redirecting some of the heat from that engine block can save your radiator some trouble and keep it going a few more miles

      • MissingGhost@lemmy.ml
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        2 days ago

        My car is a diesel so it takes a long time to warm up in the winter. They added an electric auxiliary heater to compensate. The air is really hot within seconds.