When running your Car’s Air Conditioner in Winter is a Good Thing

By Automotive Staff | November 18, 2008
Run my car’s air conditioner in the middle of winter, with 6-foot snowdrifts all around? Are you out of your mind?” This, no doubt, would be a classic retort among some drivers to a suggestion to switch on the A/C, even when temperatures on the outside are hovering near the freezing mark—or even if they’re just a bit brisk. But don’t dismiss the advice out of hand—after all, your car’s air conditioning compressor doesn’t just refrigerate the air. In fact, it doesn’t even need to refrigerate it, unlike your home air conditioner, which is permanently set on “freeze.” You can dial in the heat setting on your car’s climate control while simultaneously running the air conditioner’s compressor. It turns out that what the A/C is really good at is dehumidifying the air—and that’s the perfect thing to alleviate those fogged-in windows that develop when outside temperatures are low and interior temps aren’t. Adding the heat setting is a bonus, because it helps the human occupants of the passenger compartment, who might otherwise complain if 40° F. air were blasted at them, even if it did clear up the condensation on the windows. Some vehicles with automatic climate control run the air conditioning compressor when the heater is on as a matter of course, but if you have a manual climate control, remember to run your air conditioner with the heater periodically, if not most of the time.
Running the air conditioner also helps keep the components from atrophying over the winter—it prevents loss of the refrigerant, and keeps up the service life by preventing expensive repairs down the road. via Auto Channel
Asher Green
Asher Green

I don't understand why you would run the AC in the winter.   The atrophying part makes sense but that should be done periodically and preferably automatically as I can't be bothered.  But When the temperatures drop, the moisture in the air also drops.  Cold air cannot hold as much moisture in the air as hot air and therefore, the AC being mostly a dehumidifier would be rather ineffective because there is not a whole lot of moisture to remove to begin with.

The car AC from what I've been told is the same as the house AC, and when the temperatures are cold, the liquid freon doesn't compress into gas as easily as it does when it's hot, so wouldn't you wear out your compressor awfully fast if you ran it such cold temperatures?

Someone please explain why my car insists on running the AC in the winter?  I have the automatic feature and invariably the AC will go on at some point when the "Full Auto" setting is on.

So, what am I missing here?


I thought everyone did this? Drives my kids crazy! It's the fastest way to clear those foggy windows, and I only run it for a few minutes.