yeah, auto defaults to blowing at your feet and will adjust fan speed depending on what temp you select....

 

I've seen in Auto that it depends what temp you set it at as to where it decides to blow the air. High 70's it will blow on your feet. Mid to low 70's it blows on feet and through dashboard vents.
As said before, press the mode button to over-ride auto choices to blow air where you want if you don't like it's decisions. Notice too that when you press defrost, it turns on the A/C by default. You can always press A/C to off and still blow through defrost, but puts it in Manual mode. Just play around with it and I'm sure you'll figure it out.

 

Think of AUTO mode as a "set-it-and-forget" it mode most of the time. Put it in AUTO or AUTO ECON, dial in the temperature, (I use 65 in the winter) and let the system do its thing. In the winter it won't do much of anything until it has some warm coolant going through the heater core. As the engine coolant temperature increases it wil slowly ramp up the fan speed directing the air out of the floor vents. As the cabin temp nears the setpoint, the fan speed will start to decrease until it reaches a steady state condition. If the temperature inside the cabin get higher than the setpoint, the system will direct somewhat cooler air out of the dash vents, even using the A/C if needed to bring the temp down. This happens a lot on sunny winter days triggered by the sun sensor on the top of the dash. By the way, the cabin air temp sensor intake is below the igniiton switch on the dash by the driver's right knee. Looks like a small louvered window. At least in the 04 it is. This behavior is independent of the temperature setting's value, no matter what the setpoint is the system will do what it has to do to hold that setting.

The difference between AUTO and AUTO ECON modes is that with the ECON mode, the A/C doesn't run as much. This give a slightly higher inside humidity since the A/C isn't on full time like it is in AUTO. I'm pretty sure that if the outside air temperature is too cold, the A/C doesn't run at all even if the A/C light is on.

Yes, you can alter the system's apparent behavior by moving the temperature setting up and down but that kind of defeats the whole purpose of having an automatic control system. Do you constantly play with your home's thermostat? The G's system works the same way except unlike most homes, it automatically switches between heat and A/C as needed. There are home systems that do that also.

Of course, it still allows complete MANUAL control if that's what you want to do. Me, I'd rather drive than putz around with the climate control.

If you have dual zone climate control you can set independent temperatures for the driver and passenger. This works because the dual zone systems have split heater cores and independent control valves/flappers for the vents. The manual has a good explanation of how to adjust each side independently or in unison.

As to DEFROST, that is pretty much manual all the way, particularly with the fan speed. Once the engine starts to warm up you can raise the temperature and the fan to your liking. Of course the A/C will come on to dehumidify the air which is then heated by the hot engine coolant. This gives the best combination for defrosting, hot and dry air. The A/C is not needed for DEFROST as much in the winter as in the summer when the relative humidity is a lot higher.

One interesting thing I have seen with this cold spell is that after warming the car up to my setpoint, the system switches by itself into a mode where it starts blowing warm air out the floor vents and the defrost/window vents. The mode diagram shows an arrow at the driver's feet and the defrost symbol is on, no arrow at the driver's face. I think this may be triggered by the single digit outside air temperatures we have been having here in PA in the morning. My theory is that this is done to keep the windshield warm and prevent possible ice forming. It doesn't seem to do it though with slightly higher outside temperatures.

Overall the G's climate control is pretty sophisticated and takes a little bit to learn and playing with to understand. It's not perfect, see the posts about how to get just fresh air in w/o the A/C coming on and with some of the issues with RECIRC mode. So dig out the manual and resign youself to a little experimenting.

 

... and cold air sinks... Come on, haven't y'all taken physics!? jk

 

Oh wow, kswan53 just wrote a dissertation on the G35 climate control system!! LOL

 

Yeah, got a little carried away I guess,

But I had read a few posts on people's issues with the climate control that I thought it would be good to have one place to collect the info together.

 

jesus ...I got my 03 g35 sedan 55k miles w/navi,premium pkg for 18k OTD

 

My buddy got 1 with same miles for 22k and a free wash.lol had some scratches though