This is 100% normal!!! The purpose of the defrost mode is to clear the fog off of the front windshield on the inside as well as provide heat to thaw ice on the outside. The air conditioning system has the ability to defog the windshield because it removes the moisture/humidity from the air that passes through the evaporator. Moisture/humidity is what causes the windshield to fog up in the first place. Some vehicles give you the option to use the A/C in defrost mode but some don't. My truck does. I may drive with the defrost on but if the windshield starts to fog up, I just hit the A/C button for a minute or 2 and it goes away. It won't make it take longer to heat up if the temp setting is on HOT. The heater core is the last thing the air passes through before it gets to YOU. It'll go through the evaporator first, and if it's set to HOT, the door will direct it through the heater core and then out the vents/defrost ducts. Don't worry about it, basically, is what I'm saying. I just thought I'd tell you WHY it does that. Hopefully you got your money's worth. Thanks for the donation. Every donation helps us remain able to help when you need it.
If this doesn't answer your questions, or simply doesn't satisfy your curiosity, get back with me and we'll keep going. Merry Christmas
Dec 24, 2008 at 9:47 AM
