Car HVAC Explained – Climate Controls to Chill Out

It might seem ironically amazing, but the climate control system in your car is probably much more advanced than your household HVAC system. Let’s learn how to get the most of all these features and functions that probably most people never bother to really understand.

I like to look at a climate control system in terms of four or five buckets of what it does:

1) First most important one is are you in manual mode or are you in auto mode.

If you’re in auto mode all you got to do is set a temperature and that’s it…the car should seek of that temperature. It’s gonna modulate the amount of heat or cool source it has…it’s gonna modulate the airflow…which Vents it’s using…fan speed and turning all of those up and down or on or off to seek that target temp.

2) Single or dual systems…many cars have dual zones.  You can sync them together so the drivers knob controls everything…or you can separate them so driver and passengers can set their own temperature and their own flow of air.

With a good climate system that’s all you got to do…that simple. Unfortunately…some climate systems aren’t always that smart.

3) Flow controls – flow controls are things like blowing down to the floor…blowing up to the defrost or blowing across the center vents.  Those are usually your main three levels.

Related to flow is the RECIRC button…or recirculation.  What this does is it takes the air in the car and basically keeps recirculating it as opposed to drawing in a lot of air from outside the car. You use this in a couple of typical situations:

• One when you’re driving through some place where the air is really stinky like when they’ve just done some asphalt paving…or you’re driving by the sewage plant [gross]…turn on the RECIRC button.
• Or if you’re in a really hot place and you want to cool down fast…RECIRC takes cold air from the air-conditioning it’s on makes it colder and blows it back into the cabin. It’s an infinite loop of cold and the quickest way to cool off. It may be called Max Air Conditioning or Recirculation…but they tend to be the same thing.

And if you’re going to roll your own and not use a lot of these sort of shortcuts and automatic settings then you’ve got two things to deal with besides the flow we just talked about.

1) The Temperature – in “manual mode” when you set the temperature up and down you’re really telling the car to give me a certain amount of air conditioning…and maybe heater heat as well…sometimes it’ll use both to hit a certain temperature of air.  But then you’re deciding what to do with that. It’s not seeking a target temp anymore…that’s all on you.

2) And of course Fan Speed decides how much you want to blow that mix of air you just created into whatever vents you just selected.

Honestly I like to use an automatic system but know this…every cars automatic system seems to be calibrated very differently.  71 degrees in one car does not equal the same feel as 71 degrees in another car. The numbers are kind of relative.

But once you find what number is comfortable for you…the car should do a really good job of keeping the cabin consistently at that temp.

See – Read More