Someone help me understand why the A/C comes on when you turn on the defroster? Doesn't make sense to me. Just curious.

2002 honda civic ex.

 

Dean, this has been standard practice now since the mid to late 90's. The reason why they do is simple. When the A/C runs, it dries the air in addition to lowers its temperature. As a result, it makes the process of defrosting the windshield that much more efficient and removes the condensation faster. Hence when you put the climate control to defrost, it automatically engages the A/C.

The a/c is very similar to a dehumidifier except the A/C blows out cold air while the dehumidier though it dries the air, blows out slighly hotter air than the room + 1 or 2 degrees.

hope this helps.

btw that why the a/c units all have condenser coils that condenses the water vapor and lets it drip outside just like a dehumidifier.

 

So when you run the defrost what is the ideal temp setting on the temp control ****?

 

Any temp but warmer the better if you are cold.

 

i dont have a/c and when it rains i cant see **** unless i take a cloth and wipe my window clean (yes i have the defroster on) without a/c the defroster isnt even worth having (at least in FL)

 

hamorhead, I know exactly what you mean. My older car used to have no A/C and so defrosting the windshield was a nightmare.

 

only if you dont have a towel or shirt laying around lol