When it’s turned on, it closes a damper and prevents air from circulating to the rear of the cabin (which in turn allows the fan to ramp down, saving energy and lowering noise when you only need air in the front row). Nifty trick is that it activates itself based on seat (or seatbelt) sensors.

 

Wow that was fast. Thank you. Interesting and nice feature, since I rarely have a back seat passenger.

 

Hmmmm.....is there an "S-flow" button on the Prime? I have a "Sync" button on the AC system ....is that what this discussion is about?? Thanks....

 

Owner’s Manual, p. 396-402

 

I had originally thought that the S-Flow (Smart Flow?) button only turned on or off the rear seat vents. Further research indicated that when the button is illuminated (On) it is in automatic mode. When it is not lit up (Off) it's in a manual or override function. If the system is on and there is a front seat passenger, it turns on the passenger's vents. If there are rear seat passengers, it also turns on the rear vents. What was really impressive to me was that the fan speed would also be adjusted so that having the additional vents on didn't deprive the driver of their air flow.

EDIT: I tested it last night with a rear passenger in the car. The S-Flow button does not work as I had thought. Apparently when the light is off, the system is off and the vents work like a conventional car (all air going to all vents). The only thing automatic is that it seems that the fan does increase speed to compensate for the additional flow paths. When the light is on, the system will provide additional air to the front seat passenger, but cuts off the air to the rear seats. Some other post indicated that the seat sensors or the seat belt switches in the back seats would control the distribution. This doesn't seem to be the case, and the graphic of the front seat passenger getting air, but an X mark for the passenger getting air seems to simplistically describe the operation of this switch.

Bottom line, if you have back seat passengers who would appreciate heated air or air conditioning, then be sure that this switches light is off.

 

I had originally thought that the S-Flow (Smart Flow?) button only turned on or off the rear seat vents. Further research indicated that when the button is illuminated (On) it is in automatic mode. When it is not lit up (Off) it's in a manual or override function. If the system is on and there is a front seat passenger, it turns on the passenger's vents. If there are rear seat passengers, it also turns on the rear vents. What was really impressive to me was that the fan speed would also be adjusted so that having the additional vents on didn't deprive the driver of their air flow.

Great explanation!! Thanks!

 

Automakers should stop including owners manuals because so many people prefer to be ignorant rather than educate themselves. Save the trees!!

 

How about a searchable PDF file? Seems contents & index of paper manuals don't always do the trick.

 

According to the (poorly written) manual, S-FLOW stands for "Front Seat concentrated airflow mode" and is described as the following:

This function automatically controls the air conditioning airflow so that priority is given to the front seats. When the front passenger seat is not occupied, airflow may switch to only the driver’s seat. Unnecessary air conditioning is suppressed, contributing to increased fuel efficiency.

Front seat concentrated airflow mode operates in the following situations.
 No passengers are detected in the rear seats
 The windshield defogger is not operating
While operating,

illuminates.

■Manually turning front seat concentrated airflow mode on/off

In front seat concentrated airflow mode, directing airflow to the front seats only and to all
seats can be switched via switch operation. When the mode has been switched manually, automatic airflow control stops operating.

Press on the air conditioning operation panel and switch the airflow.
 Indicator illuminated: Airflow to the front seats only
 Indicator off: Airflow to all the seats

■Operation of automatic airflow control

●In order to maintain a comfortable interior, airflow may be directed to seats without passengers immediately after the hybrid system is started and at other times depending on the outside temperature.
●After the hybrid system is started, if passengers move around inside or enter/exit the vehicle, the system cannot accurately detect the presence of passengers and automatic airflow control will not operate.

■Operation of manual airflow control
Even if the function is manually switched to directing airflow to only the front seats, when a rear seat is occupied, it may automatically direct airflow to all seats.

■To return to automatic airflow control
1 With the indicator off, turn the power switch off.
2 After 60 minutes or more elapse, turn the power switch to ON.

 

I liked at the end where it said that even when the system is switched to direct airflow to only the front seats, when a rear seat is occupied it may automatically direct air to all seats. Now it seems like it’s a switch with a light to indicate whether is it on or off, but may or may not control anything.

I’m also confused about the end of the section where it says how to return to automatic mode. “With the indicator off, turn the power switch off.” “After 60 minutes or more elapse, turn the power switch to ON.” Seems strange that it would take an hour to reset something. More importantly, what is the “power switch”? I hope that they really meant the indicator switch and not that the car has to be turned off for an hour.

 

I would like to thank you 8AA for making my previous point. The OP asked a simple question in a short 3 part sentence. All of us who haven't read the manual ( I don't even know where mine is ) and don't care to read it, sat back and read 8AA findings, posting of the actual manual instructions, and he/she even took the time to load up a passenger in the car to determine how S-Flow actually works. All the while I watched some football, a supercross race, ate a few meals, and made some condescending and inappropriate posts in this thread and others. This is a great Forum, thanks 8AA. I'm sure some of the techies and former IT guys will break down each bullet point in the manual into some mind numbing detail in future posts and debate when the " S Button " should be pushed or not pushed. Looking forward to it, NOT.

 

Clearly. I stated this is a great forum but you cherry picked a portion of my attempt at a humorous ( I thought is was humorous ) statement. Is slab a reflection of your personality ?

 

Clearly. I stated this is a great forum but you cherry picked a portion of my attempt at a humorous ( I thought is was humorous ) statement.

Apologies, obviously I missed it. Didn't miss the 'former IT guy' comment though.

Is slab a reflection of your personality ?

No, it's a reflection of my name actually. I'll assume that's another attempt at 'being humorous', as it doesn't make a whole lot of sense otherwise. All good regardless.

 

You just said it, it reduces the fan speed and total airflow and thus total cooling provided.
You don’t need to cool the rear of the car if nobody is sitting there.

Engineers (particularly at Toyota and particularly for their hybrids) spend a lot of time reducing energy use wherever they can by using smart design. This is one of those cases.

Not sure why you’re so up in arms about it. You bought the car in part because of how efficient it is, right?

And the duct is already there. Not sure what you’re on about.

 

The icon seems to indicate that if you wish to have air directed at your face, refrain form carrying a large box on your knees.

dp

 

^ it is very efficient. the a/c design and it's ability to be more efficient is far more advanced than back in the day.
every bit helps and with electric a/c

eco mode, can save 2mpg to 4mpg on my common trips when it is 90deg out
s-flow on, so only driver zone gets cooling ? 1 or 2mpg by itself

yes the rest of the inside doesn't cool off as much, but it blows my driver vents cool
and I don't care about the rest of the interior if I feel cool.

turn s-flow off, mpg hit. turn eco off, mpg hit.

 

Since the a/c is electric, I don’t believe an increase of 2-4 mpg is possible using either of those settings. The a/c electric draw is low, and does not directly affect gasoline consumption as there is no belt, and mpg relates to the ICE. I can imagine a tiny improvement in efficiency from these measures, but not large enough to calculate in trip miles per gallon, especially since daily trip variables such as speed and traffic are much greater. If you use the eco DRIVE mode that makes a real difference as it affects response and fuel usage. And I don’t, and don’t plan to, as I enjoy using occasionally what this vehicle has, which is 302 hp. Otherwise, I’d have purchased a Prius.

 

sorry but my 2022 hybrid shows noticeable and repeatable improvement/worsening of mpg
by messing with s-flow and/or eco button (not eco drive mode, eco button on a/c controls).

4 to 5 mpg sometimes. I do the same 10 mile trip twice every stinking day and know when my mpg is 55 or 50.1
by doing exactly same driving and several rounds of tests with my a/c modes. temp fixed at 64 in the display, 90-92deg outside.
1/2 my tests I throw out because traffic situation required a change in throttle or cruise.

all 'clean repeatable runs' I did show me mpg improvements or losses

eco a/c mode works and s-flow works to save gas.

 

You can believe it, I don’t. Nor do I believe you are getting 55 mpg from the ICE energy alone on a repeatable basis unless you hypermile in slow traffic. Yes, those a/c settings “work” to improve efficiency, but not that well. As I wrote, the a/c is electric, not belt driven.

 

Slab, I agree with your statement. I'm one of those elderly folks who has minimal computer savvy. I appreciate those who take the time to 'spoon feed" us older folks. Thanks.

 

Absolutely nothing can be done to both save me any energy or get any sort of proper cooling out of the R4P in a Texas summer. I've been absolutely suffering in this thing all summer to the point of driving my Lexus GX460 more guzzling petrol but has a brilliant AC just to keep from frying like an egg in my prime. And this of course has a huge impact on range. At least this is only my 3rd small complaint of the vehicle.

 

One thing that I think is often overlooked is that while individual energy savings might be smallish, the aggregate effect of many of these smaller energy savings can really add up to a much more efficient car.

A little here, a little there and soon you are talking about a significant amount of energy savings.