So lets say you are going to drive somewhere after your car has been sitting in the summer heat for hours. What is the fastest way to cool down the interior air so that the car becomes more comfortable?
If you have a remote starter, you can let it run the AC for 10+ minutes before you use it. But thats not always an option.
In my experience, I turn on the car, turn the AC up all the way and then leave the drivers side door all the way open for about 15 seconds. That tends to get rid of a lot of the hot air.
Does opening the sunroof and turning the AC on work to push the hot air out of the top?
What about opening the passenger windows while opening and closing the drivers door repeatedly? I think that can create a pump to move air through the car. Or I guess you could open the sunroof and then open and close the door repeatedly.
Having lived in Phoenix and Vegas for years, and now Miami …
yeah, @glee nailed it. Prevention greatly helps reduce the amount of cure needed.
Beyond that, here’s my max-results recipe:
Open all car doors. Lower all windows and open sunroof if available. Start car, set AC to Max. Stand outside the car. As soon as the temp inside is tolerable, not comfortable, close all the doors, hop in, and drive away with the windows & sunroof still open. After a mile or so, close the windows and sunroof.
You may find you don’t need all those steps. e.g. I usually don’t bother with the passenger side door(s), nor the lift gate if the car is a hatchback / SUV / etc. But those steps will get you the most results with the least wasted time.
I drive an old-fashioned and not particularly tricked out pair of vehicles. No sun roofs or remote starts.
The key is to get the hot air out of the vehicle.
I usually do that by opening both doors for a minute or two even before I start the vehicle. If doing so might not be a good idea (you’re in a parking lot and don’t want to bang the car next to you or whatever) at least roll down both windows. That way you exchange overheated air for the cooler air outside.
Start the vehicle and get the fans/AC going. As those are starting to blow cooler air shut the doors, roll up the window, and proceed to capture the cooled air.
If you have a sun roof as noted the hottest air will be happy to escape upwards.
What LSLGuy said. You need to simultaneously rid the car of hot air and also put cold air into it. So that means opening the doors and having AC on cold blast at the same time.
And driving for best results. That blast of relative wind is what gets the hot air out, gets a lot of airflow over the super-heated interior surfaces of the car that will keep heating the air for some time, and moves as much heat as possible as soon as possible.
After a mile or so, so a couple - 3 minutes, the diminishing marginal returns set in and it’s time to let the HVAC blast cold air directly on you for comfort as it slowly bleeds the heat out of the interior structure.
This. The difference with and without a windshield heat shield is silly huge. They’re a bit awkward to store and deploy, but once you’re good at it the few extra seconds when parking and when leaving are more than paid for by much nicer interior conditions lots sooner.
A lot of the heat will be in all the solid parts of the interior, like the seats, dash, etc. The stale air has just a tiny bit of the heat and is easily swapped with outside air. What takes a while is for all the heat that’s in all the solid material to dissipate. Using a sun shade can greatly reduce the amount of heat that gets into the solid material in the first place so there’s less heat to dissipate. A silver sunshade is best since the shiny material will reflect suns rays back outside. A dark sunshade will absorb the rays and radiate some of the resulting heat into the car. Tinting the windows can also help reduce the heat that gets into the car–especially the back window if it’s slanted. But once your car is hot, you want as much airflow through the car as possible to pull out as much of the stored heat as possible. Some car ACs will have a smart recirculation setting that will initially pull in outside air to push heat outside, but will switch to recirc mode once the car has cooled off.
One thing I’ve wondered is if a water mister could help cool the car off. These are like the ones in hair salons that put out a fine mist, like this:
Spraying a light mist of water on the hot surfaces of the car should cause the water to pull heat out as it evaporates. Then the airflow will push the moist air out of the car along with its heat.
That’s great if shade is available. In a typical outdoor parking lot, or in my own driveway, it is not. A very good solution for me at home is to pull in to the garage, which also tends to be a lot cooler than the outside on a hot summer day for the same reason that it’s warmer in the winter.
But if there’s no rain in the forecast I’m often lazy and leave the car in the driveway instead of maneuvering into the garage (it’s a kinda tight fit because of all the junk in there). So then I have to deal with one of the suggested remedies on a hot day. There is no sunroof so I just open the driver’s side door for a minute. Sometimes you can literally see ripples of heat pouring out, indicating how much hotter the interior was than even the ambient outside temperature.
My guess is that the cooling effect would be absolutely negligible, and hitting a hot painted surface with cold water might actually be bad for the paint finish.
The fastest way would be to open the sunroof and pour several hundred gallons of slushy ice water into it, probably. Or, open the sunroof and fill it to the top with liquid helium.
On business trips to the Phoenix area, I was surprised by the amount of surface parking lots. I would have thought there would be more underground or covered parking.
I was thinking more of misting the interior of the car, like the seats. Not the exterior of the car. It’d have to just be a very light misting. Just enough to evaporate quickly without leaving the interior damp. Probably not really practical or needed in cars with good AC, but might be an option for someone with a weak AC or no AC at all.
This is reminiscent of so-called “swamp coolers”, ersatz “air conditioners” that work by blowing air through a wet porous material. These are, in effect, humidifiers, and in any but the very driest desert climates, they make the situation worse by making it more humid and even more uncomfortable. I doubt that they work well in even the driest climates.
The problem is that isn’t always an option if you park in the parking lot of an apartment complex or parking lot of where you work.
I thought it would be the opposite. The car trying to pull air from outside which is 100F would be cooler than the car trying to recycle 180F air inside the car.
Well, if you open all four doors first, then the inside air should be pretty close to the outside air. Then, close the doors and set it to recirculate.
Or, fill it to the top with Bose-Einstein condensate, a few hundredths of a degree above absolute 0. The bigger the temperature difference, the quicker it will cool.
