Anyone else notice that if you turn on the Auto climate while the car is still 'cold' it will keep the fan speed on a lower setting and gradually increase it while the car warms up? I thought that was kinda neat, I drove a TL for a while and if you put it on Auto it would blow full blast regardless of how cold the engine was.

 

I HAVE noticed this. The problem is that when it's very cold you get very little air circulation until the engine has warmed significantly. I would rather get a little lukewarm air than none at all.

 

I too have my A/C button turn on when I press the auto button. So if you are right, then does at a certain point the A/C turn off automatically? Obviously in cold weather you don't want cold air, you want hot air. Also, I have many times manually turned off my A/C in cold weather and my windows don't fog up.

 

Yeah but honestly it only works great sometimes. Most of the time even when the car warms up the fan speed stays in between low to medium or just medium and here in NJ it gets very cold (especially today with all the snow/sleet). Also, the computer doesn't really a good job directing the flow of air as it mostly goes pointing the legs.

 

Not that I don't trust Gernby, but can someone confirm this? Anyone ask a tech? My girlfriend drives around in her BMW with the A/C lit all the time. I always thought that meant that the compressor was on and that she was killing her mileage even when she was blowing hot air out the vents.

 

If the A/C light is illuminated in auto mode, does it require more fuel consumption? Regular A/C in hot weather obviously eats up gas so do you think it would have some effect in Auto mode in cold weather?

 

besides the a/c being on to remove moisture, the a/c light being on doesn't mean that the compressor is actually running the entire time. the ecu will turn it on when it deems necessary, like when the humidity increases inside.
when you have your temp set on a warm temp, warm air will blow out compared to outside air, whether the a/c is on or not. it's just like the thermostat in your house, except the a/c has to be available to dehumidify the interior the car.

 

So essentially, there's no real point in not having the A/C button lit. Not having the A/C button is the equivalent of "Economy Mode" in a Benz.

 

You can manually set the fan speed anywhere you want it, before it warms up.

Koz

 

I think it memorizes your last settings???

 

In the auto mode the temp and fan speed are utilized/automatically adjusted to reach the set temp. This works very well. If the fan slows that means you are reaching the set temp. The system wants to be running the lowest fan speed and maintain the set temp. If the fan slows and you still feel cold, you need to increase the set temp. You can manually raise the fan speed but the temp will not increase. The system selects the best combination of vents, fan speed and temp with the use of the sensors, to achieve the set temp ASAP. It works very well once you find comfortable set temp. Set it and forget it! I manually disable the A/C as much as possible to save some fuel.

Koz

 

That is what "automatic climate control" is all about, I wouldn't sweat the small stuff.

 

Depending on what the system senses (temp, humidity, etc) the A/C compressor will cycle on and off to achieve your desired settings. If the system doesn't need A/C to achieve this, the compressor will not engage, even with the light lit. If the light is manually turned off the compressor will not engage. Remember, if you make any manual adjustments the A/C light will light. This includes raising/lowering the temp or setting the system to full defrost.

Koz

 

Has anyone considered looking at the manual? It's probably very clearly documented what the A/C button light really means.

 

The compressor in our car is not simply "engaged" or "disengaged". Rather than cycling on and off, we have a variable displacement compressor that is able to vary it's capacity depending on load, engine demand, etc. In cool weather, the compressor will run with a very small displacement, dehumidifying without exacting a large fuel mileage penalty.