So everyone knows that the defrost setting cycles the A/C (there's even a thread for disabling it). I was just wondering if anyone knows the particulars of how this works. . . for instance, is the compressor on the entire time you're using defrost, or does it just cycle for a little bit? Can we expect any effect on mileage when using defrost constantly? Thanks.

 

On my GD3 I took an extended trip that past June and it was humid enough to need the defroster, plus that crud Honda left on the inside of the windshield made it worse so I left it on the whole time. That was about 225 miles across da UP after dark so I could see the lights dim every time it engaged.

The compressor wasn't running the whole time, but it was dimming the lights every couple minutes. On the bright side I got 43 mpg that tank.

 

There is a mod I posted for this problem. The defrost runs the A/C thus killing your mpg. For some reason honda thought it wasn't worth adding an additional button to turn off the A/C for defrost.

 

Found it:

https://www.fitfreak.net/forums/eco-...5-defrost.html

Enjoy! - You know I never did this mod, too lazy I guess.