Air Conditioning, Recycle the air or not?

<div class='quotetop'>QUOTE(sl7vk @ Jul 17 2006, 11:21 AM) [snapback]287631[/snapback]</div>

Recycle. It is always more cost effective, summer and winter, to only heat or cool inside air. Constantly pulling in outside air means that you are cooling or heating outside air. Modifying outside air is always noticeable as the system appears to not cool or heat adequately. Maintaining inside air is always more cost effective.

 

The Prius is smart, but sometimes it needs help. If the cabin temperature is really high (like when you first get into the car), the system will assume that it's not cooling fast enough and will start recirculating the air. It's best to open the windows and let the air temperature inside the car become about equal to the outside air. Then you can close the windows and let the air conditioner run with the air recirculated (this is equivalent to the MAX AIR setting on conventional vehicles). If the system is in AUTO, after the cabin temperature gets close to the temperature you've set, the recirculation will be turned off automatically. If it is very hot outside, it will be more efficient to turn the recirculation mode back on. However, the Prius is all about efficiency, and even when recirc is turned off, the car will still be recirculating most of the air, and only bringing in a small percentage of outside air. With recirc on, 100% of the air will be recirculated. Assuming that your passengers are pretty good with their hygiene, there is nothing wrong with this mode, but I think the cabin gets a little stuffy after awhile. Also, I assume that the exhaust air passes over the batteries to provide cooling. However, in recirculation mode, I'm not sure where this excess air would come from.

 

<div class='quotetop'>QUOTE(sl7vk @ Jul 17 2006, 03:45 PM) [snapback]287689[/snapback]</div>

Well then open a window for a minute or two. I agree that recycling the air is most cost effective. That's why just about all modern airliners do it. Yet another parallel to aircraft technology.

 

If the car's been sitting in the sun, I open the windows for a minute or two to get out the hottest air. Then I run it on automatic. I make adjustments by the temp setting and let the car figure out what to do.

The Prius A/C is the best I have ever had in any car I have owned.

 

I have tinted vent visors on all four door windows. When I park the car, I lower all the windows about 1-1 1/2 inches and install the sunshield in the front windshield. When I get back in the car, I start the car, turn on the AC in recir mode, raise the windows and make sure the temp is set to 78 degrees F. I also have the darkest legal tint on all windows and hatch glass which helps.

 

I really need to get tinted! I do the same with rolling the window down to let out the hot air. I do find that in the heat it is best to just adjust the temp and let the auto AC work. I point my vents up toward the ceiling as I don't like it blowing hard on me, dries out my eyes. The cool air circulates better and the car cools quicker. Way more efficient and comfortable than the old SportTrac!

 

What is the best tint to buy that won't discolor or bubble and tolerates 106 degree south Texas heat?

 

got a question guys, if you park your car and run the AC on the lowest setting with recirulate ON, how long would the battery last going from green to pink? did anyone idle that long to find out?

 

<div class='quotetop'>QUOTE(philmcneal @ Jul 21 2006, 10:57 PM) [snapback]290361[/snapback]</div>

It depends on the heat gradient, of course. How hot is it outside that you're trying to cool from? What do you mean by lowest setting? lowest fan speed, lowest temp?

When it was about 80°F outside, and the interior temp set at 72°F, I sat for about 20-25 minutes (in the shade) before the ICE kicked on to charge. I was at the top of the blue bars (two down from the top) at the start.

It's hard to precisely answer a vague question.

 

In general I agree with recirc, but humidity should be taken into account; both from a subjective feeling of comfort, and whatever setpoint the Prius uses (I'm presuming there is a setpoint).

I personally **HATE** humidity, but thankfully live in a high desert climate. Since getting my windows tinted, I haven't been using AC this summer in city driving -- I just open all four windows 1 - 2 inches. If my family is in the car, AC is set to auto at ~ 80 degrees.

One other point: Leaving the windows cracked open when the car is sitting is really important. Even so, the cabin heats up more than outside ambient air. I always try to drive a good five minutes before turning on AC; not only to equalize cabin air temp to outside air, but to give the dash and other plastics in the car time to equilibrate. The bloody things are heat sinks.

 

Tint the windows, open 2 in all around to get air out, recirc always....

then as you come up to a hill use the wheel button to turn air off, keep fan on...after cresting, turn air back on...

 

<div class='quotetop'>QUOTE(Salsawonder @ Jul 18 2006, 01:18 PM) [snapback]288309[/snapback]</div>

Hey, I have a SportTrac too! I always thought that was an odd combination.

The Prius does have a good A/C system. I leave it on Auto and adjust the temp from the steering wheel, letting it decide how to cool the car. I resisted this at first (I think I may have control issues), but I've found that works the best.

 

<div class='quotetop'>QUOTE(sl7vk @ Jul 17 2006, 11:21 AM) [snapback]287631[/snapback]</div>

Once again, Prius A/C is basically smarter than we think. The system has a 2-way air input, which means that it can recirc cabin air and bring in fresh air all the same time at differing levels. It was said above, but I guess I'll repeat it, even when the recirc light is off the system is still doing some recirculation of cabin air, but it is bringing in fresh air to augment the cabin air. Don't ask me about percentages of outside air vs. insidea air because I do not know. The point of this is to create efficiency by recirculating air that is close to setpoint temperature, but to not continue to recycle a 100% mixture of our breath, cabin humidity, interior odors and general BO.

Most vehicle auto climate systems react as the Prius system does when the cabin is very hot; the system turns on max, full fan and full recirculate. It would make more sense to start out bringing in cooler outside air, however auto manufacturers either haven't figured out the appropriate point to turn on the recirc or they figure that cooling down the hotter interior air and getting the later benefit of the much cooler refrigerated air over the coils when the air is brought back into the air box is better than using outside air at first. There has to be somebody that knows the logic from a mathematical point of view.

<div class='quotetop'>QUOTE(fshagan @ Jul 22 2006, 11:56 AM) [snapback]290570[/snapback]</div>

And as you have discovered the auto features work quite well.

Over the past couple of years, I have noticed that most of the folks that have issues with the Prius a/c system are the ones who have never had auto climate in a car before and are not used to letting the car do its own thing.

 

I have been doing the turn off ac to go up hills for years. Good advice.