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I don’t understand why there is the recirculation button on the screen and a recirculating button near the shifter. I thought turning on one would automatically turn on the other but it doesn’t. You can have one turned on and one turned off. So are they serve different functions?
I'll bet it works like similar buttons in my last Lexus LS. The "Auto Air circ" button in the PCS probably allows the HVAC system to go in and out of recirculation mode as necessary such as when pollution is sensed. The recirculation button on the center console forces the HVAC system into recirculation mode regardless of whether it is really needed.
Also what is interesting is when I have the air distribution off. For the up, middle and down (first picture). I can still feel the air. It’s not turned off. Vs when it is enabled. (Second picture).
So what does the “AUTO Rest” button do (1st pic
when I press it, it goes from 2nd pic to 3rd pic. And when I press the button again to turn it off, it won’t turn off. The only way to turn it off is if I use the lever to turn the air higher or lower. But then the air distribution for up, middle and down are now turned off. I don’t understand it at all.
Last edited by irvineboy; Apr 28, 2023 at 07:05 PM.
The AUTO REST is a dual function switch, depending if the engine is switched on or off.
With ignition switched ON, selecting the AUTO REST will automatically regulate the fan speed and vent output; the fan speed runs in accordance with your setting in the PCM: Strong, Medium, or Soft. As @Woofman said, the Recirculation setting is also automatic. Below 41°F, auto mode will not recirculate inside air since this may cause window fogging.
The vent selection is also automatic: Generally, A/C blows from side and center vents, HEAT from floor vents, and DEFROST from windshield vents, or a combination thereof.
So when you press the AUTO / REST button, all of your manual selections are cancelled and the PCM adjusts the fan speed and vent outputs according to your temperature selection and delta from sensed interior temperature, solar sensor in the dash, and outside temperature.
To exit Auto mode, you can change the fan speed. There are a few ways to do this: Either engage A/C MAX or Front Defrost, both of which will set the fan speed too high. A less drastic way is to manually change the fan speed a click or two. Any of these methods will turn off Auto Mode.
The other function of the AUTO REST switch is used with the ignition OFF. Press the switch to activate the Residual Heat function. The system will recirculate hot engine coolant through the heater core and blow warm air in the cabin to keep it warm for up to 20 minutes after engine shutdown. Handy on those cold winter days when popping into a shop for a few minutes.
To turn off Residual Heat with the ignition off, simply push the switch again
Thanks for the explanation. Porsche makes something that’s supposed to be so easy so complicated. So the AUTO button on the passenger side seems to turn off the air distribution for up, middle and down but just on the passenger side. And clicking AUTO does not turn it off. Have to manually use the lever to change the air setting either up or down. Is AUTO REST different from AUTO just driver side vs passenger side?
The Auto Rest button is needlessly confusing because it is a dual-function switch.
When the engine is operating, it is a simple “Auto” button for the climate control; just like every other manufacturer.
The confusion arises from the “Rest” mode. A better setup would be a separate button labeled “Res Heat”. When the engine is off, it activates the residual heat mode.
Thanks @Schnave MB has separate buttons, one for AUTO and one for REST. To my knowledge MB does not offer REST in the US market so it's nice that Porsche includes this useful cold climate feature.
Thanks for the explanation. Porsche makes something that’s supposed to be so easy so complicated. So the AUTO button on the passenger side seems to turn off the air distribution for up, middle and down but just on the passenger side. And clicking AUTO does not turn it off. Have to manually use the lever to change the air setting either up or down. Is AUTO REST different from AUTO just driver side vs passenger side?
It works pretty ,I h like every other automatic climate control. Not all that complicated. Have you not had automatic climate control before?
Hitting Auto doesn’t take it out of auto, that’s not the purpose of the button. You hit it to put it into auto. It doesn’t “turn off” the air distribution. It doesn’t show it because the car, not you, is controlling the location. If you want to override auto, you use those specific controls.
Last edited by Needsdecaf; Apr 28, 2023 at 10:30 PM.
I am just saying when you hit AUTO, the three air distribution, that were on, are not on anymore. I just assumed by the picture because I see it change when I press AUTO, the 3 buttons are not highlighted anymore.
Still don’t see how AUTO REST and AUTO are different when ignition is on. If we are not talking about the residual heat function.
Last edited by irvineboy; Apr 28, 2023 at 10:47 PM.
The function as you describe is normal. AUTO does the thinking for you including deciding which ducts to open and which speed the fan should run.
The sentence as you wrote it is correct, AUTO REST and AUTO are not different when the engine is running. AUTO REST and AUTO are the same if the discussion is not related to residual heat. It seems like you are over-thinking this.
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