[Mysterytrain]

After reading what Sal wrote I realized why I froze my nuts off all those years before I installed the footwell blowers. Growing up with American Iron, when you push MAX defrost you hear fan noise and a draft of cold air until the car warms up. Eventually, the car warms up and you turn down the annoying defrost blower. Common sense would make you think that when you are in a 911 it would work the same way. So, you pull up the floor levers and move the top dash lever all the way to the right. Your hear what you think is a the mother of all defrost blowers and you drive off thinking that once the little car warms up everything will be toasty and you will be able to back off on front blower. Well, that ain't going to happen..That front fresh air blower is blowing cold air into the cabin at greater volumes then the whimpy rear blower could ever hope to provide. So, you freeze until spring.
The beauty of the footwell blowers is that they are located at the base of the dash and can really force heated air thru the maze of ducts and vents. You can actually feel the air coming out of the vents! Amazing!
Its kind of like a hair dryer...hold it 10 feet away from your head and you feel nothing..hold it an inch away and your burn a hole in your skull.