I want to be able to blow hot air at my ice cold windshield in the -20°C Canadian winters, but American car designers are all like “oh you want to use the windshield vent? you must want the AC turned on!”
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LORDSMEGMA@sh.itjust.works 5 weeks agoDefrost setting uses the AC unit. Helps pull moisture out of the air
yucandu@lemmy.world 5 weeks ago
Thorry@feddit.org 5 weeks ago
This isn’t just an American car thing, non American brands do this as well. That’s because it’s a good idea. The heater core has way more capacity than the AC, so the air coming out of the vent will still be warm. But running the AC is still a good thing, because it gets the moisture out of the air.
Without running the AC the humidity in the car shoots up and takes a while to clear, with the AC on the humidity stays controlled. This helps clear the windscreen sooner and helps with comfort in the car. It also prevents mold, which if you live in a cold but humid place, can be very annoying. It is very normal where I live to have the AC on in fall and winter, because otherwise the humidity inside the car is very uncomfortable and can easily cause mold all over the interior.
4am@lemmy.zip 5 weeks ago
If it’s a cold winter day it’s dry outside. Just open your cabin circulator to bring in outside air, and you don’t need to use the extra gas to run the AC.
If you’re in an equatorial area, foggy windows will be because of unbelievably high humidity in hot to boiling weather, which WILL require AC because you can’t just suck in more wet air and make it hotter and expect that to work.
yucandu@lemmy.world 5 weeks ago
I would like to have the choice, because of fuel concerns.
HeyThisIsntTheYMCA@lemmy.world 5 weeks ago
i’ve never fiddled with an a/c system that denies you the choice, but i haven’t fiddled with them all yet.
MnemonicBump@lemmy.dbzer0.com 5 weeks ago
Is -20°C regular winter temps for Canadians? It’s colder than that here in Minnesota
ryathal@sh.itjust.works 5 weeks ago
Where most Canadians live it doesn’t get particularly cold. Toronto is south of Minnesota. There are places that get really cold, but not many people live in most of them.
ceenote@lemmy.world 5 weeks ago
Air conditioners pull moisture out of the air by making it colder, reducing the amount of moisture the air can hold. Its not doing anything if the air is already colder than the air conditioner can go. The air conditioner will only help if it’s 55F/13C or more, where it will only fog up if you live somewhere very humid.
SchmidtGenetics@lemmy.world 5 weeks ago
The moist air freezes to the coils of the ac unit, which is than heated by air and drips out of the vehicle through a condensate drain.
How do you not understand that basics of an air conditioner? It doesn’t just cool, it conditions the air.
ceenote@lemmy.world 5 weeks ago
That doesn’t even make any sense. Is it cold air depositing frost onto the coil, or hot air melting the frost? It can’t be both. You know that frost building up on coils is a huge problem that breaks air conditioners, right? Frost clogs the air stream, and creates a feedback loop where the coil gets way colder than it’s designed to because air can’t pass through.
I could have been more specific: the air conditioner can be useful in rainy or foggy warm conditions where the air conditioner can still cool the air further, and a car air conditioner goes colder than a home air conditioner does, around 38-45F (3-7C). It can also help if something in the car is adding moisture to the air, like if the occupants are sweating. However, when it’s just a cold day fogging the windows, the air conditioner does not help. It does not have a mechanism to dehumidify the air other than to cool it.
SchmidtGenetics@lemmy.world 5 weeks ago
Uhhh… why do you think they have defrost cycles?
If you turn off the ac for a short period of time, you run heat over the coils to remove all the accumulated frost, snd switch over again. This just used air instead of heating the coils with a reverse loop.
You say others are just using Google and ai, but clearly you’re the one using those tools and have no experience.
ayyy@sh.itjust.works 5 weeks ago
I’ve never found a more confidently incorrect bunch than HVAC people. I’ve never understood what it is about that profession specifically that causes people to just turn their brains off. See also: the absolute disdain for heat pumps and the absolute insistence on massively over sizing furnaces everywhere by HVAC technicians.
LilB0kChoy@reddthat.com 5 weeks ago
I don’t have a side in this but both my ‘93 Ford Escort and my ‘01 Ford Crown Victoria would turn on the A/C compressor if you hit the Defrost button for the windshield.
Cort@lemmy.world 5 weeks ago
Wouldn’t it be more efficient to pass the cold dry air back over the hot side heat exchanger to increase its moisture caring capacity before blowing it at the glass?
You know like a dehumidifier?
CADmonkey@lemmy.world 5 weeks ago
Probably, but the hot side of the car’s AC is outside of the car typically in front of the radiator.
Natanael@infosec.pub 5 weeks ago
Air conditioners make it cold inside the unit at a condensation surface, collecting the water there.
That’s not how you defog a window, you heat the window until the air in contact with it can hold more water and so the water evaporates faster due to both water and air temperature. THEN this air can be pulled back into the AC to deposit it there with condensation.