Gen 4 HVAC usage and settings?

a warmer setting should provide improved mpg's. eco only suppresses compressor operation, so achieving lower temps is more difficult.

 

I have a 2009 Gen II and in summer used to run with the A/C off and the windows cracked open just a tad (especially easy with deflectors), but this summer in the fierce heat & humidity, I've been setting the A/C to AUTO, the temp to 78 (or sometimes 72) and letting the Prius's brain do its thing. I've noticed that on short runs with the A/C running the SoC indicator goes up and down, like the proverbal "Whore's Drawers", and I have a ScanGauge II which confirms that and also displays the Voltage of the Traction Battery, but on the longer runs, the SoC quickly settles down to all greens, and the voltage is around 230-240. I think running the A/C causes the MPG to take a slight hit, but heat is the big enemy of the Traction Battery, so the cooler the interior of the car, the better it is for the battery (the air-intake for the Traction Battery is inside, by the right shoulder of the rear passenger on the right-side).
In the colder weather I block the grill (see threads passim) and usually wait for the ICE to kick in (and sometimes run until it shuts off) before moving the car. - hope this helps - Wil

 

You probably don't care what us low-life Gen 2 owners think. Probably get more Gen4 owner replies in those forums.

 

I guess I think differently. I want total comfort in the cabin when it comes to hot weather. I'm not concerned about a 1 or 2 MPG loss because I am running my AC.

I use the AC 90% of the time, in normal mode, not "Eco." It's very nice. (I also want the cabin to be cool for the Hybrid battery.) My MPG is always a steady 60-62; I am very satisfied with that.

 

For comfort in the really hot weather, go for Normal

 

...and I always have the Temp set at 65, in the summer.

In winter, I'll bump it up to 68.

 

I don't use the AC much, and this is 3rd gen experience, car in Normal mode. Anyway, what I do:

1. Set Auto and AC button on.
2. Raise temp setting until fan speed stops racing, settles down to about half of full speed. This can mean temp set as high as 28~30C, if it's really hot
3. As cabin temps stabilize and fan speed drops, adjust set temp downward. Typically I'll settle on 25C as final setting.

 

You confused me. A bit too complicated.

I don't use that "Auto" setting.

My AC is already on when I start the car. The temp is always at 65. The fan speed is always on low...

Go buy an Egg McMuffin.

 

It's been near, or at 90 most every day in my area. But very low humidity. Terrible fires going on.

Auto AC on full force: Yes, that's why I just use the manual mode. I can set my own fan speed.
But when I did use Auto, every time I lowered the fan speed it would disconnect the Auto mode... So now I just use manual all the time.

 

Assuming in regards to setting the AC at 25C, it works good at that temp, feels surprisingly cool. 24C at the lowest.

 

People must think I'm nuts for saying I have my temp set at 65 degrees. Even in the morning. But I'm a big man, and I always feel "warm." (It's my fault for being so heavy. Not good!)

When our "winter" comes (which means it could still be 80 on Christmas ) I hope we get some nice cold weather. I might like to actually try out the heater in my Prius.

 

Times 9/5 plus 32, nothing to it. 24C's about 75F.

 

I turned my A/C on in 1976, and it's barely been off since (OK, off mostly in winter) - if it's hot, the A/C is on.

The Gen 4 AUTO mode seems to have a mind of it's own - it will sometimes turn AUTO off if I select RECIRC - then 5 mins later, it will happily allow it. Other times, if I want it to deliver air to FOOT+FACE, it will turn AUTO mode off as well and later reverse it's decision.

There are 2 ECO Modes - if you select ECO Mode for the CAR, it will set the A/C to ECO A/C Mode. But you can also have the car in POWER or NORMAL Modes, and select ECO Mode for the A/C.

I went for a drive last week, it was a warm, but not hot day (28 max I think), A/C between 23 & 24. I noticed that in AUTO "DriverPriority" A/C mode, + RECIRC, FOOT+FACE, sometimes it wasn't cooling enough, so turning Driver Priority OFF, it cooled much better - I flicked it between ON & OFF a few times. I'll work it out one day.

 

I thought the ECO air setting reduced the air out of the passenger and rear vents. Fine with me, assuming it's blowing on me. I do notice the temperature differential from the actual to the desired will increase the fan speed and open up the passenger vents. My normal temp setting is 65. It does very little to the fuel mileage. Actually I never looked at it, nor do I care when it's 100 at 95% humidity. That said when it's a nice day the windows and the sun roof are open.

 

I keep mine on 68 Auto, ECO, Driver Priority and that's really as cold as i ever want it. Sometimes ill even bump it to 70 because its too cold. With 68 i still get out of this world MPG so i'm happy with it

 

I think either method would have almost exactly the same effect on mpg, because you are adjusting both modes until they are doing the same thing as each other. I suggest you use the method that is most comfortable and convenient for you.