Getting non-preheated outside air

The last half dozen car I've owned (various makes) were like that. The vents travel through areas that seem to be warm and the vent air is never the same as the straight outside air. I just use the AC as it does not affect fuel mileage very much these days like 25 years ago.

Does it get cooler after a few minutes? All cars I've owned have acted this way after sitting in the sun. Basically, the car gets heat soaked in the dash and cowl area where the air intake and ductwork is located. When you first start out these warm components preheat the incoming cool air. However, most of my cars will being to deliver air closer to ambient temperatures after a few miles of driving, but it certainly takes a little while to cool things off. I generally use the AC for a few minutes to cool down the ductwork and then switch to outside air.

Matt

That depends a lot on the particular car in question. The A/C cost me at least 3 mpg on the highway in my Elantra. On one of the Elantra sites, someone did dyno runs with and without A/C. The A/C cost him 17 horsepower! Judging by the way the car reacts when I turn it on, that seems entirely plausible. It makes sense that it's less of an issue with cars that have more powerful engines and get lower mpg to begin with, but it still costs you.

As for the windows down vs. A/C debate, it all depends on the particular vehicle in question. Some may do better with the A/C on, but my Elantra does better with the windows open.

BTW, I've found a method that works very well for cooling the car, without excessive noise or drag. I tilt the sunroof open, open the rear passenger's window 1/3-1/2, then open the front passenger's window

2"-3". This creates a swirl in the car's interior that cools very effectively, even at modest speeds. The windows can be opened or closed to regulate the amount of airflow. I can still listen to the radio comfortably, as I don't have the noise from having the driver's window(s) down.

That's what I've seen as well.

I also usualy leave the ac on for a few minutes & if it was real stuffy just tilt the sunroof for a while too. I want to ask something slightly related though a bit off track>

I have read here that it is best to not use the recirculate feature with the ac to prevent the form> BETA-32 wrote:

few minutes? All cars I've owned have acted

No, but I know what you mean. I keep expecting that it will get cooler but it never does. I have a feeling that something in the system isn't allowing the heat function to completely turn off. If I had a manual control, I would move the heat control all the way to the coolest position. In every car I've ever owned, when I did that only cool or cold air would come out. This seems to be functioning the way it would if a manual control wasn't turned all the way to the coolest position.

I don't have a sunroof, but if I did I wouldn't want to have to open the sunroof or anything else just to get cool outside air into the car. I have a hunch that even at the lowest temperature setting there is still some hot water going through the heater core and partially heating the incoming air.

Why not, that's what it's for. I didn't say that it was mandatory (obviously you wouldn't use it if it was raining), but it does increase airflow through the car when using the vents, since it gives the incoming air an easier exit point. It also lets out the warm air near the ceiling.

No, there isn't. The issue is heat from the engine compartment and sheet metal.

Exactly. You have a choice between interior pollution and exterior pollution. The interior air filter will remove most particulate matter (the Elantra doesn't come stock with this filter, you have to install it), but it won't remove chemical pollution. You could make your own filter element using filter media with carbon in it, but it's debatable how effective it would be.

It's possible that you car is malfunctioning. There should only be a few degrees difference between inside and outside air temps when the heat is off. It sounds like you need to take the car to the dealer.

It is my understanding that the fuel savingis speed dependent. At low speeds drag is les than the air conditioner uses. At speed somewhere above 30 MPH the air drag drom the open windows uses more fuel than the air conditioner. As they say, YMMV.

;-)

And vary it will. The mpg numbers I quoted above are for highway speeds.

Ahah! I just figured it out today!

To do what I want, I set the temperature to "Lo", which is one click below the lowest actual temperature option of "63 degrees". That automatically turns ON the AC, which I do not want, and the "recirculate inside air" option, which I also do not want. Then I turn OFF the AC, and I switch from the "recirculate air" setting to "outside air". That lets outside air -- at whatever temperature the outside air is -- come in through the vents without ANY preheating. That's what I wanted. And I don't have to open any windows or sunroof to get non-preheated outside air in, which is also what I wanted.

If I click the temperature setting up just one click, from "Lo" to 63 degrees, I can immediately feel that the incoming air is being preheated. I think it does that because, if the outside air is say 55 degrees, and it thinks I want 63 degrees inside the vehicle, it naturally starts to preheat the outside air to help bring the inside vehicle temperature up. But, by selecting "Lo", it is not governed by any specific temperature setting, so it COMPLETELY turns off the preheating of the air that is coming in. It seems to work in the same way that a manual heater system does when moving the temperature setting "off".

That makes sense. It would be interesting to see what the actual temperatures are and if it does rise anyway on the path through the ducts. Even on cars with no automatic AC, or even no AC, it always seems to have a noticeable gain.