Remember the outside temp doesn't really have anything to do with the AC. If you have been parked in the sun so the car thinks it is hoter than the 72 you've requested it can run the AC to try and cool down the interior. I found on Friday with mine between the sun shinning in the roof all day and then hitting the temp sensor below the fan speed control it thought the inside was hot and wanted to run the AC. I just turned the temp up from 72 to about 75 and everything quit and I was quite comfortable.
Its probably "remembering" how you want it to work. See my post above.
With the fan off very little air enters the car, there isn't a strong ram effect. Recirculation doesn't affect that, just whether air comes from outside or inside the car. With the recirculation switch in auto recirculation is off except when the car detects bad air, you wash the windshield, select reverse or for specific climate functions (recirculate on to heat up or cool down faster).The manual also claims that it is a bad idea to leave the fan off because no fresh air will enter the car! I think this is nonsense; that is what the air recirculation switch is for, and I detect some air movement when the car is moving. I suppose they worry about sitting in a traffic jam. Got to suck those exhaust fumes in so you can breathe!
The one thing that should be automatic, which apparently is not, is shutting off air recirculation after a while. Other vehicles of mine have this feature and it makes sense.
The manual on page 232 recommends leaving the A/C switched on all the time! For visibility, but I never have much problem with that. Maybe in a heavy rain it's a good idea.
What is this "heat zone" you speak of? Climatronic has digital setpoints.
If you have Climatronic turned off and you press OFF again, it will wake up and restore to your previous settings. Pressing AUTO will wake it up in automatic mode (with the AC on). Pressing other buttons will make it wake up into the mode for whichever button you pressed.Salsaman06 said:
I was having difficulty trying to describe the behavior of the Climatronic that I was observing. The use of "heat zone" was my word choice, not that it is some official nomenclature out of the owners manual or factory shop manual.What is this "heat zone" you speak of? Climatronic has digital setpoints.
What I was referring to was moving the temp dial to a setting (any setting) that would cause heat to flow out of the registers instead of cold air. That range of temp settings (the zone if you will) that produces heat from the registers varies depending on the interior temp. That's what I meant by "heat zone". 
You have an automatic rear view mirror? What does it do?
Don't let the mechanical details discourage or confuse you. The A/C button works the same as it always has because the physics behind it all has not changed. When a compressor is operating, it consumes energy from the engine (read that "burns more fuel") The difference between the old compressors and the Passat's is that the old compressors consume a fixed amount of energy from the engine as long as it's engaged. The Passat has a variable compressor which varies the amount of energy it consumes from the engine based on the demand for conditioned air. Over the long term, the Passat's variable compressor should consume less fuel than the traditional "fixed" compressor. But if you want to make sure it consumes the absolute minimum amount of energy, press the A/C button and turn it "off".Boy this is getting complicated. Makes me pine for the days with a lever controlling a cable controlling how much coolant went through the heater. Crude, but you didn't need a PhD to operate it.
I guess I will just get in the habit of looking for the A/C light and killing it whenever I see it, except when I want it. A pain in the butt.
I really do like that automatic rear view mirror though. Sometimes real progress is made...
EXACTLY... Just adjust to ONE click off coldest setting, and turn off the A/C and recirc (which also automatically lights up!!!). It happens to me too.
On the manual climate control, you hypothesized that the temperature control knob corresponds to a setpoint, rather than just directly setting the RCV or heat flapper. Do you think the setpoints maintain a set temperature coming out of the vents or in the cabin as a whole?What is this "heat zone" you speak of? Climatronic has digital setpoints.
If you have Climatronic turned off and you press OFF again, it will wake up and restore to your previous settings. Pressing AUTO will wake it up in automatic mode (with the AC on). Pressing other buttons will make it wake up into the mode for whichever button you pressed.
As mentioned in an earlier post, the Passat has a variable output compressor via a refrigerant control valve. The compressor itself is always spinning, unlike an older compressor with a clutch that cycles. As you approach your zone temperature setpoint, the compressor unloads itself to maintain the desired temperature as efficiently as possible (older systems add heat rather than unloading the compressor). This is why there is very little fuel economy penalty for A/C use with Climatronic.*
Climatronic:
read more: http://my.vw.com/2012-passat/comfort/climatronic-heating-cooling
Manual Climate Control:
read more: http://my.vw.com/2013-passat/comfort/manual-climate-control
With the manual climate control, turning the temperature knob to the position shown in the pic (MAX A/C) will enable the compressor and engage the recirculation function. The detent on this knob position is very small and is easy to inadvertently select. If the system is off and you press OFF again, I suspect it will behave like the Climatronic system and restore to your previous settings.
On both climate control systems, pressing recirculate will also enable the compressor. This prevents humidity (from your breath) from building up in the cabin and subsequently fogging up the windows.
-----SIDEBAR-----
I think, but have not confirmed that the temp dial on the manual climate control actually corresponds to a zone temperature setpoint, rather than just regulating a heat flapper or valve. To explain it a little differently, I think that, for example, straight up on the temp knob could be 74 degrees and you can go up and down from there. The computer will automatically regulate the compressor load and/or add heat as necessary to maintain your setpoint. Any HVAC gurus out there feel like doing some testing?
*Before someone points out the RCV in previous TDIs (dating back to the ALH and maybe before?): that only regulates the refrigerant flow based on evaporator temperature - not based on zone temperature like the new models.
