Heated Over the Defrost: Why Do They Make Your Car Defroster Automatically Use the Air Conditioning?

Seriously, if anyone knows the answer, I'd like to know. My previous car was manufactured in the late 1990's and in the instruction manual it advised you to turn the Air Conditioning on when defrosting your windshield. While this is understandable on days where the humidity is so high it steams up the inside of the windshield, most days it is not necessary. Therefore I rarely ever followed these instructions.

My current vehicle was manufactured in 2008 and to my chagrin, it automatically uses the air conditioning when you turn on the defrosters. I do not like this one bit. Here is why:

- As I stated before, most days the air conditioning is unnecessary. Heat by itself works just fine to clear the snow and ice off the windshield.

- Air conditioning in the car makes the engine work harder, which means more fuel is used and more wear and tear on the engine

- Air conditioning naturally cools the air, which means it doesn't get as hot as just using the defroster alone

I find it extremely annoying that we don't even have the option to turn the Air Conditioning off when using the defrosters. In fact, it doesn't even acknowledge that the Air is on by lighting up the Air Conditioner button. The only reason I know the air conditioner is used because of the way the engine kicks in hard when turning the defrost on, just the same as it does when using the air conditioning in the summer. (And because it doesn't get as hot as just the heater does.)

Since I live in an area where we get extreme cold in the winter, there are many days where it is necessary to keep the defroster full blast on the windshield to prevent snow and ice from developing in your view. I would much rather NOT have the air conditioning on during these days due to the above mentioned reasons, especially with fuel prices being so high and threatening to go even higher.

I really do not understand why car manufacturers thought it was necessary to always have the air conditioner on when using the defrosters. Were too many people getting into accidents because they couldn't figure out how to keep the inside of their windshields from fogging up in cold weather? I sure wish they'd make it optional again.