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Old 06-06-2016, 01:44 PM   #22 (permalink)
mwilliamshs
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Join Date: Apr 2015
Location: USA
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VanDelay - '89 Ford Econoline E-150 XL
90 day: 15.93 mpg (US)

Old White Civic - '98 Honda Civic LX, AT
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Quote:
Originally Posted by hayden55 View Post
Here's what I mean. And from what I've heard from upper level engineering students taking hvac classes thats spot on. Generally thought most modern systems measure inside and outside air, pull in the cooler of the to, then start pulling that air through the ac. So for me in the mornings and when you first start your car on a sunny day its better to pull in the outside air until it feels cool in the cabin, then once it feels nice start recirc the inside air.
That's true. Typically better to use fresh air than recirculated when first starting a car that's been parked in the sun because the air trapped in the vehicle will typically be hotter and more humid than what would enter the vehicle's fresh air inlet while in motion so recirculating and conditioning it would require more work than conditioning fresh, flowing air. Once the volume of air trapped in the vehicle has been exchanged with conditioned fresh air, begin recirculating for best results. If you're starting the car but not driving away (inefficient) like using remote start to cool a parked car, etc, recirculating from the start can be a better option. In reality we're talking about just a few minutes of time at most, so do what makes you feel good.

Better option is of course to not park in the sun except in cold weather and to vent the vehicle in hot weather.

Last edited by mwilliamshs; 06-06-2016 at 01:54 PM..
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