rainforest

I own the GS450h, but was wondering about the smog sensor/auto re-circulate function. If I place the ventilation on auto recirculate, it defaults to having the air conditioning on. But isn't this a waste of fuel, having the air con on even during the winter? Or does the auto re-circulate shut off the air con when it is too cold? Please explain.

herbvdh

Having the A/C on acts as a dehumidifier so your windows do not fog up in the winter time.

Balnk

I have always thought it was funny when people associate A/C with
cold air. Air Conditioning has hot air also. I can understand why people
get confused, the controls on the dash are misleading.

It should just be a temp setting with a button that is for the "dehumidifier"

rainforest

But even if hot air comes out of the air con and dehumidifies the cabin, doesn't this still waste gas?

JHStrange

any pump/fan/CD/radio/etc. that is driven by the engine requires some amount of power whether it's mechanically or electrically driven. I don't know of any studies on the fuel impact but it has to be minimal; certainly compared with driving styles, going up hills, starts and stops.

I suppose if you added it all up, you'd get something measurable over a tank of gas in a controlled test but you didn't buy a Lexus to be concerned about that.

Balnk

I have done several UNscientific tests with my GS430.

Full tank of gas, AC always off, ran till empty.
Then...

Full tank of gas, AC always on, ran till empty.

The result......


No difference.
Got about 315 miles out of both tanks.

Franknyc30

wow thats an interesting point. i had a female friend who was cheaper than the day is long. on those hot summer months she would torture anyone who was in the car with her (her kids included). you could be melting your nuts off and all she would say is "open the windows the breeze from the car will cool you off". in any event, whenever i had the choice of car pooling or using my own vehicle, i would use my car. i never understood sacraficing personal comfort for the sake of saving a buck. or in this case pennies.

Irishman06

Ahh, here's the kicker: the hybrid has a high-efficiency electric compressor, which uses even LESS energy than those old belt-driven ones!

rainforest

So, sounds like the point is to leave the auto recirculate on all the time. Thanks for the test results on your GS430.

Julez

I too wonder why anyone drives with the air on and A/C off. It gets so stuffy inside the car and the air isn't even cold(or hot).

Jace7

technically I believe, the gs450h is able to run all electrical completely on the electric motors alone. And when you are breaking....coming to a stop, the regenerative breaking actually charges that batteries back up..... so it's not a waste of gas. it might eb a waste of electricity. i have the gs450h, and that's what my advisor told me......

jwa

Electric AC does run on the hybrid battery, but my experience so far has been that when the temp get's above 90 outside, the battery drains so fast that the engine has to run almost continuously to keep it charged. The other downside to electric AC is that it doesn't work nearly as well as conventional AC in hot weather. Now that it's cooler outside, I don't notice that much of a difference in performance, but I was less than thrilled over the summer.

Keep in mind that the recirc mode doesn't determine if the AC is on or off; It determines if the air being circulated comes from inside or outside. With the recirc mode set to auto, air flow should be external unless the sensors detectect pollutants and changes it to internal. It should automatically change back to external when the pollutants are clear. IMO, there is more hazing and fogging of the inside windows when the airflow is left on internal for long periods.

Similar to rainforrest, the recirc mode on my 450H always defaults to internal or external - it won't stay on auto. I ask the dealer to reprogram the preference for auto, but they told me it couldn't be done on the 450H. I know the GS300 stays on auto, so either my dealer is wrong, or they made this change for the 450H. What's the point in having an auto setting if I have to manually set it to auto every time I start the car?

rainforest

Hey Pole. There is something wrong with your car. My 450h is ALWAYS in auto mode if I set it to auto mode. It always remembers the last setting I had it on. If I leave it on fresh air (non-auto), it will stay this way even the next time I start the car.

Secondly, whenever you press the auto button, it ALWAYS turns on the a/c. Press the climate button, and you will see this. That's why I was wondering if I keep the system on auto all the time, and hence air con on all the time, won't this use up more gas?