Speed Fan...

[koolyce]

Hi,

I have a question, a really easy question for you.

When I turn off my fan, no air blow inside UNTIL I drive. Faster I drive, more air come inside by the vent.

It is normal?

I mean, at low when I drive at 110km/h, the vent blow pretty fast and also, the fan start making a little noise, like it goes too fast.

Thanks

[philipa_240sx]

koolyce,

The HVAC system (fan) gets fresh air from the vent located near the edge of the hood behind the windshield wipers. This area at the base of the windshield experiences high air pressure at speed. The faster you drive the higher pressure and more air will be forced into the HVAC system. This is why you feel some air even with the fan turned off.

BTW, this high pressure area was exploited by car designers back in 60's. They used to duct the air cleaner intake to the back edge of the hood to take advantage of the slightly higher pressure. I'm not a car history buff, but I believe the Chevy Camaro was one of the first to do this... they called it 'Cowl Induction'. A similar type system has been used on NASCAR stock cars for years. I'm sure you muscle car fanatics know a lot more than I do about this... if so please chime in.