HVAC Question................. Is AUTO the best setting?

Auto is convenient as all get out. While it's not THE most economical, it's far from the least economical. Most of the time, I set my desired temperature and leave it on auto. This time of year in FL, I usually have it off altogether or might just run the fan on speed two with the air conditioner off. If it's chilly enough and my wife is with me, I'll put it back on auto if she's not satisfied with the seat heater. And then there's the odd time when I need to blow some condensation off the windshield.

But those are in the minority over the span of the year.

 

I've only ever used AUTO with RECirculate. Adjust the temperature occasionally.

AND if I want to cool the car quickly, I press this - which brings in vents to all positions:


Not sure, in USA, yours might look like this:

 

i've never used auto, i can't stand the loss of control

 

It's the only way to get Gen 4 A/C working.

 

alanclarkeau,

And here in the USA our water goes down the drain clockwise whereas your OZ water goes down counter-clockwise.

 

really? count me out. no more temp gauge, a/c button and manual fan control?

 

They're there, but it won't A/C unless you press the AUTO button - you can over-ride it by turning A/C off - then AUTO isn't really auto, and change the fan control, but it works that out well itself. AUTO won't interfere with Recirc/Fresh though.

But as far as I know, there is no way of putting the A/C on without pressing AUTO. The manual only talks about the:


No Manual.

 

ugh. i guess the that makes the o/p's question a moot point

 

I far prefer a Manual transmission

 

Different models have different control layouts, but I think they work about the same. My Prime Premium is radically different in user interface than most Gen 4 models, but works the same way.

Back to the original question, though, Auto is by far the most convenient. Like @alanclarkeau, I keep mine mostly on Auto with recirc. But I often override that. One thing I do a lot here in the summer is turn off recirc until the cabin cools down to close to the same temperature as outside. It's quicker AND more comfortable to cool 95F air than 135F air. Or I'll increase fan speed to suit my wife. Both of those will turn off the "Auto" indicator.

 

I like the auto feature especially in the winter months. I usually hit auto then deselect the AC unless I want it. The nice thing in cold weather is the fan will not blast you with cold air. The auto waits until the engine is warming and gradually brings up the fan as warm air is available. SO much more comfortable. I set it that way and forget it. It will also modulate the air where needed. Then I add the AC when needed only on a hot day. I have happily used it that on my last 2 Prius.

 

And I doubt that it has any measurable impact on economy, versus doing the settings manually.

In every car I've ever owned that has that setting, it stays on AUTO most of the time and just the temp setting gets moved up or down a bit.
The exception to that, as you mentioned, is when the outside temp is around 70; some manual adjustment might be necessary.

 

Really? I have had my car set AUTO for my first summer, but this summer I have kept AUTO off most of the time. If you have AUTO off, but A/C on, wouldn't it turn on the A/C for cooling? I sware I could get cold air coming out of the vent using that setting, but I am not 100% sure. Maybe PRIME is different?

At least under my use case, keeping the PRIME in AUTO during winter had a very big hit on EV range due to heavy reliance on the heat pump for heating. The car tries so hard to keep the ICE off and use up the battery by running the heat pump. It turned out switching to HV manually and keeping the climate control manually set to low fan speed is doing a much better job in saving EV range for me. Yeah, for many places where running EV is much cheaper may benefit by keeping the climate control in AUTO and minimizing ICE use is economical, but for where I live, gas is cheaper than electricity, the AUTO climate setting cost me more on charging cost.

 

I've noticed that using AUTO in winter months (or like now) it will actually keep my car running while stopped at a light. As soon as I hit the off button the ICE shuts down. Mine is a Prius C however. Not sure if that makes a difference.

 

AUTO is the most convenient setting since it adjusts the fan and vent settings automatically to keep the cabin at your desired temperature. The AC button is independent of the AUTO button in the sense that pushing it ON or OFF will not change the AUTO setting. You can still remain in AUTO with the AC light off. Selecting a manual vent or fan setting will turn the AUTO light off.

 

On our 3rd gen, the ONLY way to turn the system "on" is to push "AUTO". A request for Toyota: how about an "ON" switch? Perhaps it could even bring it back on, as you had it it set previously?

Heady stuff...

 

really? i just turn the fan on and the system comes on. i can either raise the temp for heat, or press the a/c button for cool. 'auto' never comes on.

maybe they updated 2012?

 

Really? That could be an "easter egg" I've missed (for 9 years), will try that. I know on our Civic Hybrid, if I'd turned it "OFF", then hit the fan speed up it would restore it, as it was. Seems to me I tried that on the Prius, no luck. Could be a CDN spec thing too. But yeah I'll give it a try.