vlad_a

Peter, the AC is not likely to be running with 6C outside, unless windshield vents are used.
However, when it is 16C, that's a whole different story.
I'm a little away from my RX right now: across the Irish Sea from you. It is also about 6C and very windy.

Silvex

vlad_a, <Peter, the AC is not likely to be running with 6C outside, unless windshield vents are used. >
Good point. Thanks.
I had not thought of it like that.
I am now though.
It could explain why I seemed to feel little difference in air quality
whether I thought, the A/C was on (green light, indicating stand-by in this case), or off.

Although I have to say that I noticed very slight fogging of the rear window
when the A/C was not "on".
So there must have been some humidity in the cabin (my wife and I).
I feel having the A/C on would have fixed this fogging.
So, it might be working a bit at 6C after all?
Oh boy ..... ...
Confusion.

< ..I'm a little away from my RX right now: across the Irish Sea from you. It is also about 6C and very windy. >
Funnily enough, it's windy here too right now.
But no snow at all here yet. Good.
Even though in meteorological terms, it is the last day
of Winter tomorrow, I believe!

Peter

Silvex

I've recently come to the conclusion that because most of us have a variable displacement compressor in our cars, the compressor is _always_ running (when A/C is on of course).

This discussion seems to have gone dead?

Does anybody want to agree or disagree with me on this? :-(

Silvex

Marqevans

I agree on my first and second generation cars when I turned off the air I definitely got better mileage.

Silvex

Ok, but that was not really the question I was asking.

Anyway, I'm also noticing a 5 - 10% mileage improvement.

The OAT here is around 8C at the moment.
Three people in the car earlier this week.
100 mile round trip.
Raining for the return journey.
Comfort in the cabin perfectly acceptable.
No fogging of windows - distribution vents hard set to floor/windscreen most of the time.

Why doesn't Lexus tell us about this in the Owner's Guide?

Silvex

DunWkg

Silvex,

If the owner's guide doesn't have the information you want, you may need to go to the technical manuals available online.

Or speak with someone at the dealership.

I don't think I've seen fog on the rear window. Frost yes, fog or condensation no. I rarely turn the AC switch off and rarely drive in ECO mode. Just finished a 2,500 mile trip with four adults on a journey from 20 degrees F snow on the ground to 82 degrees F sun and green grass and back to freezing and snow and only touched the temp up and down buttons. But then, fuel economy was not a concern.

Humidity was probably fairly low on our journey too.

kitlz

David, you're right. It's one of the Lexus Personalized Settings (LPS). A link to all MYs can be found in the FAQ thread. I recall reading about it in the manual too but it's been a few years, LOL! And don't forget for us 450h owners, AC is electric so it doesn't really impact mileage.

vlad_a

Anita, energy is energy. There is an impact. ICE has to do more work to compensate for the electric draw.

websailor

Agreed. Although the A/C may work via the MG set and the internal battery, it is still using energy. And the only two ways that energy gets into the internal battery is either via the ICE driving the MG to create the energy or via the regenerative braking driving the MG set. So unless you have some magic occurring where you go downhill consistently more than level or uphill driving, then the ICE/MG is going to be providing some of that energy....and the ICE uses the gasoline that you put into your car.

As an over simplification, I think that the gas I put into my tank is my sole source of energy input. Any regenerative braking is usually offset by the extra energy used going uphill. (Most of the time I do round trips, leaving and ending up in the same place - home). However the battery/MG sets allow me to smooth out my use of energy by driving more efficiently - hence the better MPG in the hybrids.

===========
Even the all-electric vehicles need a source of energy - by plugging into the electricity supply at their house or a recharging station, they are getting that energy from the local Utility company.

kitlz

Let me clarify, I do realize there is an impact. My comment was specifically about decreased mileage with the AC on. It's negligible in the 450h compared to the 350. And MPG is the way most people gage how efficiently/inefficiently their cars use energy. I'm going to stop now before I derail this thread even more. We should move the discussion over to the hybrid forum.

websailor

Back to the original thread then.

Today, even though it was cloudy, the RX got quite hot inside. As we're driving Cflutist takes off her jacket, I couldn't since I was driving. I open both front windows to cool down....she complains about the pollen, so the windows go back up. I am way too hot with my jacket on, so I hit the AUTO button. Aaaahhhh, nice cool air starts coming out. I finally did use the A/C!!!

Silvex

Ok noted. I'm sure that must be right.
When you see the size of that HVAC unit you realise it does not run on fresh-air (wrong choice of words, I know!). But you know what I mean.
It's got to affect mpg.

Silvex

Silvex

Thanks. That's helpful to me.

< ... ...you may need to go to the technical manuals available online. >
Yes. I've started to do that.
Very technical stuff.
But I'm learning a lot.

<Or speak with someone at the dealership.>
Hmmm ... I'm not so sure about that.
I think we users often know more about the subject than them!

<I rarely turn the AC switch off and rarely drive in ECO mode.>
As I said earlier, I'm experimenting with A/C OFF all the time at the moment.
It's fine.
Controlling things by TEMP, BLOWER SPEED and manual AIR DISTRIBUTION or, AUTO CC (without A/C ON of of course).
But OAT is currently 8C (no, I don't live at the North Pole!)
So humidity is quite low right now.
So less chance of fogging and misting up.

Silvex

MellonC00

how do you turn off the just the a/c while in auto mode? in my older RX, I can simply hit the ac switch and turn off the a/c and still have the auto mode controlling my fan speed, vent location (either by the foot, by the face or both) and heat amount. this was great when the weather was around 40 to 60 degrees without using up the a/c. on the 2013's I can navigate the screen to turn the a/c off. But that takes literally 4 screens to get there. any short cuts?

bobys

I have wondered myself, but I also go through the menu when the weather is mild. I do wish there was an A/C on/off button right there in the hvac control panel.