It's Summer - Air Con Usage Guidelines?

Recirculate. Outside air usually has higher temperature and higher absolute humidity, so it will take more energy to cool and dry it than will recirculated air.

 

I recommend starting the A/C with the windows open to clear out the built-up heat, and then switch to recirculate. The outside air is going to be cooler than that which has been trapped inside a vehicle sitting in the sun. No need to try to cool 130 - 140 degree air.

 

Agreed, if one doesn't mind sucking in outside dust and whatnot. After things cool down a bit, switch to recirculate.

Anyone know whether exterior air goes through the cabin air filter before it enters the cabin? From the configuration I suspect it does not...

 

I use the system on auto a/c, set to 75 degrees. When the car is first started on a hot day (in the sun), I keep the windows open for the initial drive. The car starts out on recirculate for fastest cooling, I guess, then switches itself to bringing in outside air.

However, here in So CAL, the temperature in the afternoon (so far) has not been terribly hot, and humidity is low. HOwever, about a month ago, the outside temperature was 100 degrees and very dry. The car started out on recirculate, I drove for a few miles with the windows open. Then I closed the windows as I neared the highway, and the car switched shortly to outside air.

Worked just fine. I have been getting close to 50 mpg.

 

I've set mine on auto at 73 degrees 100% of the time (N. FL.) and still getting 49 mpg over 3000 miles. I just don't think it warrants special treatment besides initially opening the windows to let accumulated heat escape. And for recirc, that's much more helpful when following a smoke belcher than trying to save a miniscule amount of fuel, IMHO. BTW, the recirc works about as well as any car I've owned....smoke belchers and other smoke is completely isolated outside of the car.....gotta luv it!

 

I just took a road trip (400 miles each way) and wanted to see if there was any difference between using auto or not. I drove at the same time of day and the temp was the same. I noticed no difference in my MPG's.

I also leave my auto on when I start my car after it is sitting in the hot sun at work all day. The fan blasts on for about a minute (hair flying), turns cool, and then acts normal. When you watch the whole automatic process you notice the car circulating from recirculating air at head to head and feet, to outside air at head and feet, and then once it reaches the tempertaure I set it at (usually 75) it rotates from head to feet.

 

I leave mine on auto, temp about 74-76, and let it do it's thing. With the higher temps (display for outside was 106-109 today, but that reads a few degrees high), I've noticed a drop off in MPG as would be expected.

Thanks,
Shawn

 

78 degrees. My MPGs are holding up better than after previous trips. Was up to 57.9MPG after 67 miles, now 51.2MPG after 187 miles.

Of course, it could be going back to Citgo gas, but that would mean one brand is different than another and that's just silly... :grin:

 

MPG comparison

It's been mostly in the 70s here in Indy with a few days in the mid 80s. With the AC on very little, I'm right in line with your results mikepaul. With about 60 miles on this tank, I'm at 57 mpg. But, if things go as usual, it'll be tough to maintain that for another 400 miles. My average per tank is 50 to 53 mpg. I haven't fallen below 50 since cold weather.
I genuinely hope the many Prius wannabees will soon be able to join in the fun. What a neat car!

 

Just use the AUTO setting and you'll be good to go!