Auto mode for heat & A/C question

One other thing, when you have the AC on say 72 and its 90 out. It may show that it is in RECIRCULATION, but the truth be known it really isn't. For a short period, usually five minutes or so, the AC unit goes to FRESH to help rid the interior of excessive heat. If you listen closely, you can hear the Fresh/Recirculate door close. You don't have to open the windows, this is a very smart system indeed.

 

I hope that helps you out. JTM

 

4r,

Hopefully this post will clear up any confusion. One thing that has not been mentioned so far is that when you select "auto" the A/C defaults to being on.

This is what I suggest. If you have problems with the windows fogging up when you are using the heat, then let the A/C run. Most of the time you will find that you will need to let the A/C compressor run in the background when you are using the heat. Most of the time when the system calls for heat the mode will default to fresh air coming in (no recirculate) if you are using "auto". On the other hand if the system calls for cool or cold air then the mode will default to recirculate. It is all controlled by the computer and will vary depending on what temperature you have the system set for and the temperature in the cabin. You may also see at times when using A/C and "auto" that the recirculate mode will be on fresh air. That generally occurs if the cabin and the outside ambient temp is about the same, usually at night.

That is what the auto is all about. It is automated so the cabin always keep the temperature you set it at regardless of how hot or cold it is on any given day.

Depending on your climate and your personal preferences, there may be times when you can turn off the heat and or the air and drive with the windows down. When doing so at speeds at or below 45 or so you can generally get better MPG. It boils down to creature comfort and keeping the traction battery temp cool.

For more information, I suggest you consult the owner's manual. Enjoy your new 2015 Prius and best of luck to you!

 

I think I've noticed the same thing, but think I read somewhere here on PriusChat that it's useful to remember that the hybrid battery is using cabin air for cooling, so it makes sense to let the system decide whether or not to kick in the A/C - (I've been getting an average of 55-65 mpg all through this hot summer!) I used to crack the windows slightly and never use the A/C thinking it would waste more energy, but I've been nice and comfy all through the hot weather!

 

Sorry Ron, I think our posts crossed!

 

It's all good. The main thing is that 4r understands what is going on. Lot's of info being shared very quickly...

 

Wait until we get "winter gasoline". It will really drop. It has fewer BTU's and a higher flash point, for startability during the winter. It sucks, IMHO. Its made for the regular ICE cars than do need it. I wish we could get summer gas for pur hybrids year round.
Now some engineers will probably disagree. That's fine, but we all have Atkinson cycle engines in our cars. So do we really need winter gasoline anyway?

 

The Prius is like other vehicles concerning MPG and summer versus winter. The MPG will be lower when it is colder. There are many factors involved, so don't loose faith. Give it time and enjoy your car.

You can look at my fuelly records and see the pattern for last year. Note, I did not drive the Prius much this year, so disregard those readings, but look closely at 2014 and you should see a pattern.

Again, best of luck to you!

 

Most AC systems, when Defrost is selected, go to Fresh air anyway. Why would you want to recirculate stale air anyway? The only times I can think of is when the air outside stinks worse than the inside. RECIRCULATION is fine in summer, not so great in winter.

Just my thoughts on it.

 

If it's really, really cold (well below 20 degrees), I'll tend towards leaving it on RECIRC because you can warm inside air faster than constantly trying to warm arctic air from outside.

You do have to watch for condensation and switch to outside air from time to time.

 

admittedly, i never use auto. i don't like the way toyota has it programmed. i like to be in 'control'.

 

Generally in a situation that you just described the heat will come out at the floor until the cabin reaches the temp you set (75) and then the air will shift to the upper areas. However if it is very cold the air may continue to come on the floor. A good example of this happened to myself and my wife when we came back from Colorado last Winter. The night we went over the divide it was a balmy 19 degrees. We had the system set on 76 auto and as I recall the air constantly was coming out of the lower outlet on the floor and did not revert to the upper vents on the dash.

Here in Texas where we live generally once the cabin is warm, the air will shift to the outlets on the dash as well as flow slightly at the lower outlet on the floor. Again a lot of it depends on just how cold it is outside.

Not everyone likes or uses the auto just as bisco illustrated above. It is up to the end user how he or she controls the system. Play with it until you are comfortable with it. There are times when auto is perfect and other times where you might want to override the settings. To override simply change one of the variable settings ie: fan speed, recirc/fresh etc.