Air Conditioner In '07 Ul Es350

[sdloeffler]

Question to anyone with the Ultra Luxury package on their ES350. Do you have to manually *BLEEP* off the air conditioner? I have the Auto switch on, and when I adjust the temperature it will automatically adjust the fan speed, but when I look at the climate control on the nav screen it still has the AC button illuminated. It my Acura, auto meant auto everything. If the temperature outside fell below the temp I had set the air would turn off. Am I missing something? Thanks.

[wwest]

Question to anyone with the Ultra Luxury package on their ES350. Do you have to manually *BLEEP* off the air conditioner? I have the Auto switch on, and when I adjust the temperature it will automatically adjust the fan speed, but when I look at the climate control on the nav screen it still has the AC button illuminated. It my Acura, auto meant auto everything. If the temperature outside fell below the temp I had set the air would turn off. Am I missing something? Thanks.

No, you're not missing NOTHING.

These days most automatic climate control systems, and MANY manual ones, will run the A/C compressor all year around unless the current OAT is below about 35F.

There are three C-best options involving this aspect of the system that the dealer can set for you.

A] You will be able to turn the A/C off indefinitely, into "manual" mode, by simply switching it off one time. It will not again operate automatically until you switch it back on, back into automatic mode.

B] The A/C can be "unlinked" from automatic operation, with no indication to you of same, in defrost/defog/demist mode.

C] The system can be "set" such that it does not automatically switch into cooling mode, airflow switched from footwell to dash outlets, once the cabin temperature rises to within a few degrees of your desired temperature setpoint.

As you have probably already noticed that cool and dry airflow striking your face and upper body during a drive when the radiant warming effects are negligible (the surrounding landscape is COLD and/or its DARK night outside) can be somewhat discomforting, if not extremely so.

But that is NOT the major point, issue with the "C" setting. As long as the system remains in heating mode, footwell airflow, some minor level of airflow is "leaked" to the interior surface of the windshield to help keep that surface warmed and not as prone to fogging over should there be an "upset" in the cabin atmosphere condition. Once the system automatically switches to cooling mode the interior surface of the windshield might be allowed to CHILL down to the dewpoint of the cabin atmosphere.

If your windshield should happen to fog over, or suddenly and unexpectedly fog over as NipponDenso and Denso US designs are very prone to do, the best procedure is to QUICKLY turn the temperature demand to MAXIMUM (the blower speed should "follow") and then switch the system into defrost/defog/demist mode. Also, it wouldn't hurt to lower a rear windshield slightly until the windshield fog clears.

Turning on, using the A/C, as an aid to defogging the windshield is a REAL WILDCARD, it may help (OAT above ~45F), or it MAY NOT (moreso the farther the OAT is below ~45F). But even worse, once the A/C is used, it must eventually be turned off and once you do that the previously "gathered" condensate will be freed to enter, flow into, the cabin.

[amf1932]

Question to anyone with the Ultra Luxury package on their ES350. Do you have to manually *BLEEP* off the air conditioner? I have the Auto switch on, and when I adjust the temperature it will automatically adjust the fan speed, but when I look at the climate control on the nav screen it still has the AC button illuminated. It my Acura, auto meant auto everything. If the temperature outside fell below the temp I had set the air would turn off. Am I missing something? Thanks.

When you first turn on the Climate Control the compressor automatically starts, and the fan speed automatically adjusts depending on the temperature you have it set to. If you decide you don't want the compressor to run, you then push the button on the NAV screen. This new setting will remain even though you turn off the engine and than restart. If you push the climate control button on the dash, it'll once again set up the climate control to the default factory settings, compressor on, fan speed regulates, temperature regulates.

[sdloeffler]

Thanks for the replies. Still not sure I undertand why Lexus has the compressor running all th time. Would think your gas mileage would be even better if it would shut off, but okay...

[wwest]

Thanks for the replies. Still not sure I undertand why Lexus has the compressor running all th time. Would think your gas mileage would be even better if it would shut off, but okay...

Yes, even in the summertime when you actually need the A/C the FE can be improved substantially by turning the system to MAXIMUM cooling (counter-intuitive, huh..??) and then using the blower speed to regulate your comfort level. If the resulting COLD airflow from the dash outlets is too discomforting change the airflow routing to footwell.

[amf1932]

Yes, even in the summertime when you actually need the A/C the FE can be improved substantially by turning the system to MAXIMUM cooling (counter-intuitive, huh..??) and then using the blower speed to regulate your comfort level. If the resulting COLD airflow from the dash outlets is too discomforting change the airflow routing to footwell.

In my estimation, this method that you suggest is not only a poor, uncomfortable, way of keeping the cabin temperature even. On top of that, it would require the compressor to run almost steadily instead of cycling on and off. This will definitely cut your fuel economy. Hey, we're dealing with a Lexus that has a sophisticated climate control system, not a plain old car that just has an air conditioner and a heater. <_<

[wwest]

Yes, even in the summertime when you actually need the A/C the FE can be improved substantially by turning the system to MAXIMUM cooling (counter-intuitive, huh..??) and then using the blower speed to regulate your comfort level. If the resulting COLD airflow from the dash outlets is too discomforting change the airflow routing to footwell.

In my estimation, this method that you suggest is not only a poor, uncomfortable, way of keeping the cabin temperature even. On top of that, it would require the compressor to run almost steadily instead of cycling on and off. This will definitely cut your fuel economy. Hey, we're dealing with a Lexus that has a sophisticated climate control system, not a plain old car that just has an air conditioner and a heater. <_<

Left on its own, automatic climate control systems will CHILL the cooling evaporator as close to FREEZING as technically possible. It must do that in order to lower the (HOT..??) incoming OUTSIDE air temperature as much as is possible to achieve the HIGHEST possible PROBABILITY of dehumidifying the airflow. Downstream of the cooling evaporator the now COLD (possibly[???] dehumidified) system airflow will be REHEATED to a reasonable comfort level via diversion of a selected portion to flow through the HEATER CORE.

First CHILL the air and then REHEAT the air...??

Sound like an efficient technique to you...??

On a HOT day that can mean the A/C compressor will run virtually continuously, if not actually continuously.

On the other hand if the incoming outside airflow is so low, say even in recirculate(***) mode, the A/C compressor can more EASILY keep the cooling evaporator nearly freezing, resulting in the compressor duty-cycle being dramatically reduced.

*** Not advisable in cool or COLD weather, ABSOLUTELY NOT ADVISABLE.

[SW03ES]

In my estimation, this method that you suggest is not only a poor, uncomfortable, way of keeping the cabin temperature even. On top of that, it would require the compressor to run almost steadily instead of cycling on and off. This will definitely cut your fuel economy. Hey, we're dealing with a Lexus that has a sophisticated climate control system, not a plain old car that just has an air conditioner and a heater. <_<

Lest you forget wwest overthinks and overanalyzes everything to the point where those reading his posts want to gouge their eyes out and cancel their DSL service.

I don't know about you Alan, but somehow I've been around automatic climate control systems in a myriad of cars for 17 years, somehow they've always just run on auto and everythings been fine. Being "ABSOLUTELY NOT ADVISABLE!" or not lol.