I want the upper air outlets open to the outside, but the fan and cooling/heating off, so when I'm driving with the windows or moon roof open there is good airflow inside the cabin. Can the air conditioning system be set to do this?
You can run the fan without AC or heat, just turn off those off and leave the fan running. This is true on any car.
Sorry, I didn't make it clear, I don't want the fan running. I want passive air flow only from the moving car.
Yes you can do that.....with it set to "vent" and the fan off. BUT the key is "good air flow" and that is not likely to happen with the fan OFF. Fan on low might suffice though. And a window needs to be cracked open a bit. With all the windows closed AND the fan off, I think you will be surprised at how LITTLE air flow you get.
You can open RECIRC: But you only get negligible - though I haven't got a sunroof so that might suck out a bit more? Very few modern cars, since the advent of A/C have had good flow from the dash vents without the fan. I well remember my first car which I had aftermarket integrated A/C fitted (had under-dash before then), the unassisted airflow went from quite good (but hot) to nearly none - unless the fan was turned on. Like almost any modern car, PRIUS brings outside (or recycled air) through 1) Cabin Filter, 2) A/C Evaporator, 3) Heater radiator - then to the vents via a mix of dampers. It's taken for granted that the fan will be running to achieve airflow - has been since the '70s.
The irony is that airflow is good with the windows and moonroof open anyway but I understand there was that setting in (mostly) domestic cars of the 90s and early 2000s. Simply turn off the climate control and ensure that the recirc button is OFF (i.e. set of FRESH AIR). That's basically the vent open and no fan running. Note that there is an air filter (like most cars since the early 2000s) so airflow won't be as strong as you may remember in your old car due to the air filter (as well as differences in aerodynamics and outside air intake position)
I found this instruction for the Gen 2 Prius. It does look like the blower needs to be used: Outside Air Vent Changing the "Air Conditioner" mode to draw in air directly from the outside for cooling rather than allowing it to be influenced by the heater-core isn’t an obvious process, but it is surprisingly easily once you know how. Many people call this "opening the vent" and it is used most frequently in the summer when you want to avoid having to turn on the A/C. Here’s how: 1. Press the "A/C" button so the yellow-bar above it disappears. 2. Press the circulation button so the yellow-bar above the "outside car arrow" appears. 3. Reduce the temperature to the lowest setting, called "Max Cold". You may alter the blowing location to any of the 4 settings available and the blowing speed to any of the 7 settings available.
