How come defrosting your windshields works better when the A/C is on?

[Syringer]

On my car, regardless of whether the temp control is on cool or hot air, when the A/C is on, my windshield gets easily defrosted as compared to when they're not...

 

[NutBucket]

A/C removes moisture from the air. Less moisture, less condensation.

 

[Legendary]

I think A/C air is dehumidified so it evaporates the water faster, beit on your skin or on your windshield.

 

[ucdbiendog]

Originally posted by: NutBucket
A/C removes moisture from the air. Less moisture, less condensation.

bingo.

 

[Ikonomi]

My car climate control has made me dumb. I never turn on the front defroster, because the car regulates temperature so that it never fogs. I've fallen into the trap of just assuming that as long as I have it on "auto", everything is fine.

 

[PowerMacG5]

Originally posted by: NutBucket
A/C removes moisture from the air. Less moisture, less condensation.

We have a winn4r.

 

[Heisenberg]

On most cars, the A/C compressor will run automatically when you turn on the defroster.

 

[Thegonagle]

On my car, the dial runs from dashboard vents, dashboard vents + floor, heat (floor), heat + defrost, to defrost only. The A/C cycles in any position from heat to defrost, at any ambient temperature above 30 F or so.

It drives me nuts and I'm going to disconnect the switch that's connected to the dial while I'm in there installing my MP3 player. I'd like to restore it to full manual control, just like in older Japanese cars, so the A/C doesn't waste my gas (or cause unsettling power fluctuations as it cycles on and off) when I don't need it at all.