Comments on: Fuel Economy Tip – Don’t Run Your Defrost to Get Rid of Morning Dew

By: fenix

fenix — Tue, 01 Apr 2008 05:03:09 +0000

I’ve heard that using the AC with heat on actually makes it more fuel economic? am I crazy?

By: bert

bert — Wed, 09 May 2007 19:28:00 +0000

Something needs to be clarified, we’re talking about the front windshield defrost right?
Not the rear.
I don’t see how turning it on for 20 seconds is going to make the slightest change in your fuel economy. I also find that using AC instead of windows rolled down and keeping the vents open when not using the AC gives me better mileage.

By: Brian Carr

Brian Carr — Sat, 10 Feb 2007 23:02:02 +0000

Cherie,

Thanks for the question. To the best of my knowledge, if you run your defrost in a car that does not have air conditioning, it won’t result in worse gas mileage. Essentially, it would be the same thing as using the vent and blowing hot air on your windshield.

In terms of newer vs. older cars, newer cars are made to be more efficient when it comes to this kind of stuff, so they will typically get better gas mileage when using the air conditioning.

Hope this helps.

By: Cherie Leese

Cherie Leese — Fri, 09 Feb 2007 15:57:53 +0000

Would you please settle a disagreement?

I think that when you use your defrost in your car, you are using more gas because the air conditioning and the defrost run off the same compressor. Even for older or newer models?

Does this same concept work if you don’t have air conditioning? Does it still use up more gas if using the defrost because your car still has a compressor?

If I’m right and your car uses more gas whether or not you have a newer or older model or whether or not you have air conditioning, would you please explain in detail how and why this concept applies or doesn’t apply?

Thank you.

By: Brian Carr

Brian Carr — Sat, 09 Sep 2006 02:33:37 +0000

Thanks for the comment. As I’m sure you can see, now that I’ve gotten past all of the obvious tips, I’ve had to start to become quite creative to continue to come up with new tips!

I agree with your assessment that most people fail to realize that when they turn on their defrost they’re actually turning on their AC. I would imagine most people think the defrost directs hot vent air.

By: Grant

Grant — Sat, 09 Sep 2006 01:52:46 +0000

I’ve been reading and collecting mileage tips for a very long time and never saw this one before. Great tip. Most people don’t realize the defroster on most newer vehicles turns on their air conditioneer compressor.