why is it some people swear that having the a/c on with the heater makes the heat work better??? have i lost my mind? whats going on here? maybe i am just crazy but it just doesn't make sense to me. Can anyone explain how this is logical or help me explain to my girlfriend how retarted this is?

 

It's very useful for defrosting windows. Th A/C removes moisture from the air.

 

ok i can understand that, but there was no need for defrosting, just wanted to be warmer so she put on both. all i can see is the air being dried out by doing this, other than that it seems like a waste of freon

 

There really is nothing about having the A/C on that will cause the vehicle to heat up any faster. The only thing that heats up the vehicle is having it running. Driving can help it heat up a bit quicker than idling, as it will usually be at higher RPMs, etc. The A/C system does not impose enough draw from the motor to get it to work hard & aid in warm up though.


Along with what others have stated, the A/C should engage automatically in MAX A/C, Defrost and Floor/Defrost. You obviously want it on when it is in MAX A/C mode. In the other two settings, it comes on to reduce the humidity of the air...which, in turn, aids in defrosting the windows.

She may have noticed that when the A/C is on & defroster is running that the window defrosted quicker. That being the case, she may have made the wrong assumption in thinking that the A/C caused the air to heat up quicker...and that the "warmer" air was what caused the frost to disappear.

The truth of the matter is actually that the frost on the windshield goes through a process called sublimation; the process by which water changes from a solid (ice or snow) to a gas, bypassing the liquid phase. It does this because the A/C system is removing the moisture from the air, and forcing that dry air directly onto the frost-covered windshield. Through some form of physics that I have no idea about, that dry air then sublimates the frost. To make a semi-educated guess, I would say that it has to do with balance. The moisture content is so low on the A/C processed air that it will wick moisture from whatever source is available. In this case, the only real source of moisture is frozen on the windshield. Hence the sublimation.


This is the same reason that ice cubes will get smaller (evaporate) when left in the freezer for long periods of time. After all, it is not like your freezer is warming up enough to let them melt & evaporate!! If it is, you have bigger problems with your freezer than "disappearing" ice cubes!