It's Summer - Air Con Usage Guidelines?

markhaney2004 · 06-01-2004, 06:02 PM

Hey everyone.

So it has already hit 100 degress here in Austin, TX. I just got my prius tinted so that I can block out a bit of the sun, but surviving the summer means that I use the air con constantly.

That being said - are there any guidelines for what is most efficient?

Should I be using the "Auto" setting?
Should I use external or recycled air?
Any other ideas?

Thanks for any suggestions!

Mark Haney
Seaside Pearl #7

richard schumacher · 06-01-2004, 06:07 PM

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.

Astroprius · 06-01-2004, 06:31 PM

Quote:

Originally posted by richard schumacher
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.

richard schumacher · 06-01-2004, 06:39 PM

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...

**efusco** · 06-01-2004, 06:44 PM

Auto, choose a conservative temp...say 80 degrees..I find that depending on circumstances and number of people in the car that anything b/w 78-81 degrees is quite comfortable while not being too demanding on the system.

I agree with recirculate when using AC. If you can, turn off the AC as you approach your destination and don't turn it on until you've done the open window thing and the ICE has begun to warm up a bit to minimize drain/strain on the system.

oxnardprof · 06-01-2004, 07:31 PM

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.

windsurfdog · 06-02-2004, 08:11 PM

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!

shocker · 06-02-2004, 08:30 PM

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.

TucsonPrius · 06-02-2004, 08:35 PM

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

mikepaul · 06-02-2004, 09:37 PM

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:

06-01-2004, 06:02 PM	#1
markhaney2004 Join Date: May 2004 Location: Austin, TX Posts: 12 My Car: Model: Package: Thanks: 0 Thanked 0 Times in 0 Posts Friends: 0	It's Summer - Air Con Usage Guidelines? Hey everyone. So it has already hit 100 degress here in Austin, TX. I just got my prius tinted so that I can block out a bit of the sun, but surviving the summer means that I use the air con constantly. That being said - are there any guidelines for what is most efficient? Should I be using the "Auto" setting? Should I use external or recycled air? Any other ideas? Thanks for any suggestions! Mark Haney Seaside Pearl #7

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06-01-2004, 06:07 PM	#2
richard schumacher shortbus driver Join Date: Mar 2004 Location: United States Posts: 7,379 My Car: 2004 Prius Model: N/A Package: #6 Thanks: 583 Thanked 756 Times in 306 Posts Friends: 0	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.

06-01-2004, 06:39 PM	#4
richard schumacher shortbus driver Join Date: Mar 2004 Location: United States Posts: 7,379 My Car: 2004 Prius Model: N/A Package: #6 Thanks: 583 Thanked 756 Times in 306 Posts Friends: 0	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...

06-01-2004, 06:44 PM	#5
efusco Troll Slayer Join Date: Nov 2003 Location: Nixa, MO Posts: 19,598 My Car: 2004 Prius Model: Package: #9 Thanks: 214 Thanked 870 Times in 505 Posts Friends: 47	Auto, choose a conservative temp...say 80 degrees..I find that depending on circumstances and number of people in the car that anything b/w 78-81 degrees is quite comfortable while not being too demanding on the system. I agree with recirculate when using AC. If you can, turn off the AC as you approach your destination and don't turn it on until you've done the open window thing and the ICE has begun to warm up a bit to minimize drain/strain on the system.

06-01-2004, 07:31 PM	#6
oxnardprof Senior Member Join Date: Feb 2004 Location: Oxnard, CA Posts: 240 My Car: 2004 Prius Model: Package: N/A Thanks: 5 Thanked 15 Times in 10 Posts Friends: 0	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.

06-02-2004, 08:11 PM	#7
windsurfdog Join Date: Feb 2004 Location: Northern Gulf Coast of Florida Posts: 67 My Car: Model: Package: Thanks: 0 Thanked 0 Times in 0 Posts Friends: 0	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!

06-02-2004, 08:30 PM	#8
shocker Member Join Date: Feb 2004 Location: Northeast Posts: 88 My Car: 2004 Prius Model: N/A Package: Base Thanks: 0 Thanked 0 Times in 0 Posts Friends: 0	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.

06-02-2004, 08:35 PM	#9
TucsonPrius Senior Member Join Date: Mar 2004 Location: Tucson, AZ Posts: 160 My Car: 2004 Prius Model: Package: #7 Thanks: 0 Thanked 8 Times in 3 Posts Friends: 0	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

06-02-2004, 09:37 PM	#10
mikepaul Senior Member Join Date: Dec 2003 Location: Columbia, SC Posts: 1,764 My Car: 2004 Prius Model: Package: #9 Thanks: 2 Thanked 2 Times in 2 Posts Friends: 0	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: