Why Do You Suppose...

[ESOG]

Why do you suppose that when you hit the switch for the front defroster on most cars it simultaneously initiates the AC as well? It is quite annoying as sometimes I forget (and my OH) always forgets and then your buzzing around town with the heat on and questioning why the car feels sluggish. This doesn't seem to be the case on some cars, but on most I've driven it is the case. Borrowed my friends 2002 Honda Accord today
and it did it when I turned the front defroster on.

[ozzerr]

its all in your head basically its the start of freakin out.

[rottie102]

ESOG said:

Why do you suppose that when you hit the switch for the front defroster on most cars it simultaneously initiates the AC as well? It is quite annoying as sometimes I forget (and my OH) always forgets and then your buzzing around town with the heat on and questioning why the car feels sluggish. This doesn't seem to be the case on some cars, but on most I've driven it is the case. Borrowed my friends 2002 Honda Accord today
and it did it when I turned the front defroster on.

Aircon ON makes your car feel sluggish? Does it have an engine from a lawnmower?

[Jayho]

:/ IDK about where you're from OP, but here in Scotland, not even I had to use my demister...

[FranKinFezza]

ESOG said:

Why do you suppose that when you hit the switch for the front defroster on most cars it simultaneously initiates the AC as well? It is quite annoying as sometimes I forget (and my OH) always forgets and then your buzzing around town with the heat on and questioning why the car feels sluggish. This doesn't seem to be the case on some cars, but on most I've driven it is the case. Borrowed my friends 2002 Honda Accord today
and it did it when I turned the front defroster on.

I believe AC dries the air counter intuitive as it may seem it is more effective
to de mist the screen with the AC on.

[Zad]

Yes, the AC element, because it is cold, causes the moisture from the air to condense on it. Thus removing water vapour from the air and so making it more effective at demisting.