Originally Posted by 2Fast4U1DAY
Even tho it seems unneccessary.... Have you ever tried to defrost a frosted over windshield with hot or warmer than slightly warm air? It gets all fogged up right? Well thats because you are blowing straight hot air on the windshield/windows... Therefore the ac IS neccessary to blend incoming cold or cool air with the with the conditioned air to make warm air to help with the defrosting of the windshield and prevent fogging.... Oh and before everyone says im insane... I just received my MACS (Mobile Air Conditioning Society) certification in the mail yesterday...
I'm 99% sure that as soon as you turn the Mode to Windshield Defog/Defrost the AC turns on, even w/o the AC light showing. It always blows cold air unless you turn it up above 75.