How to cool the inside of your car down on a hot day

[markj]

I crack the sunroof a little, drop all the windows with the AC on full blast with the lower vents, recirculate off, and drive for a few minutes like that until the cabin cools down a little. Then I switch to recirculate and close all the windows and sunroof. Quickest way to get as much hot air out as possible.

At least that's what I do when I don't have much time or have too much dignity to be jerking my door back and forth.

[MyDianaZ06]

I can't read Celsius.

If you just get in your car and drive off with the windows down and the a/c on full blast it'll cool down before your down doing all that with the door. Plus like everyone says, people will look at you and think your an idiot lol

[owequitit]

and what if its over 100* outside like it is now in austin?.. youll be "bringing in" 100+* air to "cool off" your car.. wtf?

plus you look like a moron doing that..

and yes.. fuck leather..

Even if its over 100*, it is still cooler than what is in your car. Greenhouse effect.

We routinely get in car temps well over 200*, especially during this time of year when you have to keep the car closed because of rain and thunderstorms.

Couple tricks that work really well:

1) Like someone else said, tint and window shades. That keeps the sun out, and temps down the most. It would seem obvious, but try to face the windshield cover into the prevailing sun. I have one of the Heatshield brand custom fitted insulated ones for the Si, and I was amazed at how much it reduced temps versus an accordian style generic Wal-Mart fitted one. A good 15-20* pretty easily.

2) Obviously, cracking your windows/moonroof if you can. That reduces the greenhouse effect.

3) After starting the car, open all windows fully, and turn the A/C while closing the vents. That will dissipate the hot air inside faster, and cool the A/C off faster.

4) Usually, you can drive for about 10 seconds with the windows down (no need to sit with them down) and that will remove most of the excess heat from the car. Then close them back up so you can start to cool it off.

5) There are a couple of ways to do this next step, both of which are effective. Obviously, we want to get cool air from the A/C throughout the cabin as fast as possible. The best way to do this is with organized airflow. I have done both cracking one rear window, both rear windows and one rear window with the moonroof vented. The moonroof + cracked rear window method definitely creates the most flow. Unfortunately, it is not all cold flow. What happens is that the low pressure on the top of the car, and the slightly higher pressure on the side of the car create a pretty good reverse flow in the cabin, with air coming in the back window and out the moonroof. Cracking the rear window/windows helps draw the cold air to the back of the car, speeding cooldown.

6) Since basic physics says that hot air rises, and cold air sinks, it is actually quite effective to point all of the A/C vents upward toward the ceiling. This gives the flow more unimpeded flow to the back of the car, but it also improves heat transfer with the hot air, and helps the car cool off more quickly as the cold air is always circulating at the point where the hottest air is also, improving the rate of heat exchange.

Yeah, it seems kind of silly to have that much technique, but when it is over 130* outside and well over 200* inside the car, you figure it out.

[Losiracer2]

I think the new prius has a solar powered vent fan in the roof that allows hot air to escape. That would be a good idea...if we could somehow rig that up

[cbscandal]

Even if its over 100*, it is still cooler than what is in your car. Greenhouse effect.

We routinely get in car temps well over 200*, especially during this time of year when you have to keep the car closed because of rain and thunderstorms.

Couple tricks that work really well:

1) Like someone else said, tint and window shades. That keeps the sun out, and temps down the most. It would seem obvious, but try to face the windshield cover into the prevailing sun. I have one of the Heatshield brand custom fitted insulated ones for the Si, and I was amazed at how much it reduced temps versus an accordian style generic Wal-Mart fitted one. A good 15-20* pretty easily.

2) Obviously, cracking your windows/moonroof if you can. That reduces the greenhouse effect.

3) After starting the car, open all windows fully, and turn the A/C while closing the vents. That will dissipate the hot air inside faster, and cool the A/C off faster.

4) Usually, you can drive for about 10 seconds with the windows down (no need to sit with them down) and that will remove most of the excess heat from the car. Then close them back up so you can start to cool it off.

5) There are a couple of ways to do this next step, both of which are effective. Obviously, we want to get cool air from the A/C throughout the cabin as fast as possible. The best way to do this is with organized airflow. I have done both cracking one rear window, both rear windows and one rear window with the moonroof vented. The moonroof + cracked rear window method definitely creates the most flow. Unfortunately, it is not all cold flow. What happens is that the low pressure on the top of the car, and the slightly higher pressure on the side of the car create a pretty good reverse flow in the cabin, with air coming in the back window and out the moonroof. Cracking the rear window/windows helps draw the cold air to the back of the car, speeding cooldown.

6) Since basic physics says that hot air rises, and cold air sinks, it is actually quite effective to point all of the A/C vents upward toward the ceiling. This gives the flow more unimpeded flow to the back of the car, but it also improves heat transfer with the hot air, and helps the car cool off more quickly as the cold air is always circulating at the point where the hottest air is also, improving the rate of heat exchange.

Yeah, it seems kind of silly to have that much technique, but when it is over 130* outside and well over 200* inside the car, you figure it out.

Referring to your #5, (and I know you know heat, because you live in AZ) sometimes that can be one of the worst things to do. Think of it as you would a convection oven. A convection oven cooks more efficiently than a regular oven because it circulates the hot air, which makes it easier to transfer heat to what you're cooking.
That's basically the exact same thing you're doing when you open your windows to drive around. (considering, of course that it is fucking super-hot outside, and you're not using your A/C to cool everything down, because some of us don't have A/C)
Sometime the worst thing you could do is have all that hot air circulating around.

[owequitit]

Referring to your #5, (and I know you know heat, because you live in AZ) sometimes that can be one of the worst things to do. Think of it as you would a convection oven. A convection oven cooks more efficiently than a regular oven because it circulates the hot air, which makes it easier to transfer heat to what you're cooking.
That's basically the exact same thing you're doing when you open your windows to drive around. (considering, of course that it is fucking super-hot outside, and you're not using your A/C to cool everything down, because some of us don't have A/C)
Sometime the worst thing you could do is have all that hot air circulating around.

No, and I have timed it.

The difference between the convection oven and the interior of the car is that there is no cold air source putting air into the system. As the air circulates through the car, it also pulls the cold air around with it. So while yes, you are circulating hot air, you are speeding the rate of heat transfer into the colder air, and are therfore reducing cooling times. It is sort of like if you warm up water it takes longer than if you stir it around to keep the warm water and cold water mixing. It improves heat transfer. It is also why if you take a house with the A/C on and shut all the doors, it doesn't stay as uniformly cool because the air can't circulate and mix. Besides, you don't run with the windows down once the temperature of the cabin starts to cool off. Once the temp cools down, you close the car up and eventually it cools down. That just accelerates the initial part of the process. I have also tried it with just the moonroof open, and while it minimizes the amount of hot air coming in, since it is low pressure outflow only, it also greatly reduces the amount of circulation, which increases cooling time.

[cbscandal]

Referring to your #5, (and I know you know heat, because you live in AZ) sometimes that can be one of the worst things to do. Think of it as you would a convection oven. A convection oven cooks more efficiently than a regular oven because it circulates the hot air, which makes it easier to transfer heat to what you're cooking.
That's basically the exact same thing you're doing when you open your windows to drive around. (considering, of course that it is fucking super-hot outside, and you're not using your A/C to cool everything down, because some of us don't have A/C)
Sometime the worst thing you could do is have all that hot air circulating around.

There.

[CB7/KA8]

This is a better option:

Auto Cool

[Flatline]

for those of us without A/C.....just get a swamp cooler. Pack it with ice and drive.

[PR CB7]

pneumonia???