Air Condition vs Windows Down

[ChopsQube]

Originally Posted by new92

thanks for everyones feedback. I was pretty sure b was the correct one, but wasn't sure on a and c.

BTW: Love the forum

Well like I said earlier, B shouldn't be an option as the real question is a/c with windows closed vs a/c off with windows open. Just my opinion...

[Clev]

I mitigate my A/C use by doing a little "Pulse and Glide" with it. I turn the vents to recirculate and then run the A/C on maximum until it's nice and cold, and then turn off the A/C and let it recirculate until it's just warm enough I can't stand it, then repeat. In moderate weather, I can sometimes do 5 minutes on, 10-15 minutes off. The fan stays on high to keep the air circulating, which helps.

[bgd73]

Originally Posted by ChopsQube

It has been proven by several organizations, including MythBusters and myself that driving with the a/c on and windows up is better than driving with the a/c off and windows down. It's a simple comparison that you can easily conduct yourself. There's really no reason to see what others have to say.

Although, I don't think that "B" should even be an option as the answer is clear. No a/c means less drag on the engine, and all windows closed means less air drag which in turn means less drag on the engine.

However, running with the a/c off and the windows up in the summer time in the more tropic areas of the world when you have a car with a perfectly functioning a/c system, I'm willing to sacrifice a couple MPG to be comfortable. The a/c in my first vehicle died six months after I bought it and I couldn't afford to get it fixed. I never want to repeat that ever again.

I could believe the text in bold easily. I have learned alot welding an older unibody.
it is even tougher than todays SECC computer case metal squishing like playdoh...(23 year old car)
+1 for A/C reducing resonance..it cools more than people, and keeping air clean, and electricl... even the engine gains more power. Most need to be into heavy welding of cars to know the resonance I refer to. It is not even detectable by people. A/C always helps it.

I also learned, if volume permitting, you can turn the car into a compressor, it is an upside down geo thermal trick....use the compression, and not the air down low. I would not even know how to expain myself.

This subject has bothered me since sitting nice and cool all year round in a big four door sedan...the little cars are roasters. Finding a way to keep cool (ambiguous) with smaller stuff is a tough thing to do.

[Ford Man]

The best mileage I ever got on my '97 Escort wagon was 49.85 MPG which was on a cool day and a combination of no a/c with the windows up and no a/c with the windows down on the interstate at a speed of 55 MPH. The best I've ever got running the a/c is about 45 MPG under the same conditions.

[Clev]

Originally Posted by bgd73

This subject has bothered me since sitting nice and cool all year round in a big four door sedan...the little cars are roasters. Finding a way to keep cool (ambiguous) with smaller stuff is a tough thing to do.

I believe this is the first post you've made that hasn't mentioned "3 main boxer." ;-)

[MadisonMPG]

Originally Posted by Clev

I believe this is the first post you've made that hasn't mentioned "3 main boxer." ;-)

I saw that too.


The point was made that a V8 suffered less with A/C on, which is true. A/C in my friends Escort murders acceleration and MPG. The same friends 6.9L diesel doesn't accelerate any faster, or get worse MPG, with A/C on and towing a 4k pound trailer.

[brucey]

So has anyone here done ABA testing?

[Frank]

BTW, you should always run the A/C in "recirc" mode: most new vehicles do this automatically. It's never 100% recirculation so the air does turn over, and it takes less energy to maintain air temperature in the cabin than it does to cool it down from outside temps.

Again, slow down 5 mph and you'll more than make up for it running full blast...

[sid]

I have had a homemade thermostat in my last five vehicles which cycles the A/C on and off based on the setting of a potentiometer, which roughly correlates to temperature. The circuit turns the A/C clutch solenoid on and off based on this temperature setting. I originally tried an old house thermostat, but I found the one I had had too much hysteresis, meaning it would be on too long and then off too long, so it would be alternating between freezing and roasting in the car.

[Thymeclock]

No one has mentioned vehicle speed.

If you live in a city environment (as I do) and you are only going a mile or two, it pays to roll the windows down because, aerodynamically, it won't matter if you are never going to go any faster than 20-30 MPH. That's assuming you can stand the heat and humidity, depending upon where you live. Better yet, consider owning and driving a convertible for summer months.

If you must have the A/C on, and there are times (believe me, I know) when you can't manage to do without it, short of being sweat-soaked to the skin, put the A/C on recirculate, shut it off while accelerating but turn it immediately back on while decelerating or coasting, or while at a stop light.

If you are going to be driving at highway speeds, shut all the windows and turn it on max cold + recirculate. If you get stuck in traffic, the same strategy as stated above applies. But after you have been driving a while and once the interior is already cold, it is best to keep it cold, rather than start all over again.