Let’s face it, winter is here, and we’re all about to do battle with fogged-up windows, icy air, and that one friend who insists on cranking up the heat to 32 ° celsius.

But there’s a surprising little trick that could save you some stress and maybe even a few bucks this season: using your car’s air conditioning in the dead of winter. 

AC in winter sounds about as sensible . Hear me out, because these little things could save your windows, your fuel, and maybe even your sanity. So buckle up and get ready to see your AC in a whole new, chilly light!

Advantage

Using the air conditioning in your car during the winter months may sound wasteful, but it could actually save you a whole bunch of money and make your car safer to drive.

I’m going to explain the advantages of using the air conditioning during the colder months, and if you’re lucky enough to have it, what the “auto” button actually does—because it probably does a lot more than you think.

So, why would you want to use the air conditioning when it’s cold outside? Surely, AC is meant to keep you cool when it’s hot outside. But air conditioning does more than just cool the air; it also dehumidifies it.

If it’s cold and wet outside, your windows are going to be prone to misting up. Using AC allows you to blow dry air onto the windows, quickly clearing the mist. Plus, the dry air lowers the humidity in the car, meaning even without the window defrosters on, your windows are less likely to mist up, so you won’t need to defrost them as often.

Is it possible to keep your windows mist-free without AC? Of course it is—people have been doing it for decades, and I have myself because not all of my cars had AC. But sometimes you lose the battle.

Imagine that it’s cold and wet outside, and slightly damp passengers have jumped into the car. They’re breathing moisture, and the moisture on their clothes and hair is starting to evaporate. Your windows are going to get misty, and no matter what you do, you might lose the battle and have to wipe the mist off, which isn’t ideal or safe when you’re driving.

You might think, “I’ll just do it while stopped at the side of the road,” but you can’t always pull over. You could wipe it off before setting off, but then the windows get misty again. And how will you check your blind spots when changing lanes? It’s pretty obvious—having misted-up windows is not safe.

Therefore, air conditioning can make driving safer by helping to keep your windows clear from mist, and it’s very effective at doing this. And while you might worry about cost, air conditioning has come a long way in terms of efficiency—and it did so quite a while ago.

Cost

When I say “a very long time,” I mean around 20 years ago. It didn’t happen all at once, but in the early 2000s, car air conditioning systems took a noticeable step up in efficiency and have continued to improve since. Back then, it was a noticeable change. Yes, these systems still use fuel, especially when it’s hot outside.

So, if it’s hot and you’ve got your AC running, you’ll probably notice a dip in fuel economy and a bit more spending on fuel.

But as the temperature outside cools and you think, “I don’t really need the AC on anymore, I’ll turn it off,” you’re not likely saving yourself much money. You probably won’t notice a difference because the system has likely ramped down, doing very little work and taking very little power from the engine.

It essentially acts as a dehumidifier, keeping humidity in the car lower without using much energy.

If you tend to turn off the AC for long periods, it’s actually recommended to turn it on every so often to ensure it stays functional.

Leaving it off for too long can lead to a hefty repair bill, as long periods of disuse can cause AC system failure. Many owners’ manuals, including mine, actually recommend leaving it on regularly.

Efficiency

The first car I bought with a more efficient AC system was a 2004 Seat Ibiza with climate control.

I was a bit confused when I first got it because I couldn’t find an AC button anywhere. I was wondering, “How do you turn the AC on?” A check in the owner’s manual revealed that the AC was simply on by default—unless you pressed the “Econ” button to turn it off. That “Econ” button disabled AC completely and gave you the best chance at optimal fuel economy.

In that car, I didn’t really notice a difference in performance or fuel economy with the AC on or off, unless it was a particularly hot day.

A couple of cars before that, though, I had a 2000 Vauxhall Astra with an older AC system.

Regardless of the outside temperature, pressing the AC button made the engine strain, and you’d hear the AC kicking in with a deeper engine sound. Performance was reduced, and fuel economy suffered as the engine had to work harder to power the compressor.

My current car even tells me how much fuel certain auxiliary components use, including the AC and the rear heated window. Interestingly, on a cold day, the rear heated window uses twice as much fuel as the AC.

So, it actually costs me less in the winter to leave the AC on and use it as a dehumidifier to prevent mist than to use the rear window defroster for the same purpose.

If you’re wondering why the rear heated window uses fuel, it’s because it draws electricity, and your engine generates that electricity via the alternator. The more electricity needed, the more fuel the engine consumes.

Auto Mode on Climate Control

Earlier, I mentioned that the “Auto” setting on your climate control likely does more than you think.

Its first job is to reach and maintain the set temperature—let’s say, 21°C—and keep it there. Many systems, including mine, even allow you to control how quickly it does this.

In my car, I can choose between low, medium, and high. Low will gradually reach the desired temperature, while high will run the fan harder to reach it faster.

Here’s where things get interesting. Not all cars do this, but many can: they can also control humidity. My car, which is about ten and a half years old, has a humidity sensor and an infrared sensor on the windshield. With this data, it can calculate the dew point and run the AC in a way that prevents mist from forming on the windows.

It also has two sun intensity sensors, which allow it to sense if one side of the car is warmer due to sun exposure and adjust the airflow accordingly. Some climate control systems also have air quality sensors to detect pollution outside the car, and they can temporarily recirculate air to keep it clean.

If I leave the AC on auto, it can even prevent mold and mildew buildup on the evaporator—a common issue if the AC sits unused for too long.

So, if you’re concerned about that bad moldy smell, using the auto setting might keep it away.

Cold Start

Let’s say it’s 3°C outside, and you walk out to your car with a cold interior and engine.

If you have a petrol or diesel car, you might think you need to heat it up as quickly as possible by cranking the heater and fan.

But if the engine isn’t warm, all you’re going to do is blow cold air on yourself. The auto setting understands this and will only blow warm air as it becomes available as the engine heats up. Some cars do have auxiliary heaters to help, but these are rare in the USA.

Accuracy

I find that temperatures on climate control systems aren’t always perfectly accurate.

In my Mazda MX5, setting it to 20°C makes me feel comfortable, but in my partner’s Toyota Corolla, I need to set it to 23°C for the same effect.

Not a big deal, though; once you know the “right” setting for each car, it’s consistent.

If you have manual AC, it’s still smart enough to avoid running the compressor hard when it’s cool outside. You just have to manage the temperature and fan speed yourself, which can feel like a hassle if you’re constantly adjusting to stay comfortable.

Own Preference

Honestly, the reason I probably like climate control so much is that I spend a lot of time in the car.

Most days, I’m in the car for at least three hours, and some days, like yesterday, I spent close to eight hours on the road.

If I only used my car for short trips, I probably wouldn’t care as much. But when you’re in an environment for long periods, it’s nice to have a steady, comfortable temperature without adjusting the controls every 15 minutes.

In short, yes, you can use your AC when it’s cold outside, and it can actually be beneficial. Plus, if your car is relatively new (less than about 15 years old), you’re unlikely to see a noticeable increase in fuel costs from leaving it on.

In fact, running it regularly might save you an expensive repair bill down the line, as AC systems are more reliable when used consistently.

Thus, it turns out that utilizing air conditioning in the winter is not only a good idea but also a wise one.

There’s much more to your air conditioner than meets the eye, whether it’s preventing that stinky “gym sock” smell in the spring, controlling your fuel expenses, or defrosting your windows like an expert.

Who would have thought that this summertime hero could be such a winter warrior?

Touch that AC button amiably the next time you’re venturing outside. In the winter wonderland, it can wind up becoming your new best friend!