I am trying to figure out the climate control system in my TCH. First off there are times that I am driving down the road and the heat system blows cold air out of the vents when I have it set to 67 degrees. After a while that is annoying and I turn the CC system off. When I turn it back on Auto, the A/C light comes on even though I want heat.

Maybe I am not thinking about this right, but when I think A/C I think "blow cold air" When the A/C light is on and it the car is blowing warm air, I am thinking that I am wasting gas in the car as the "cold air" must be warmed before blowing in the cabin. If I turn A/C light off, it still blows hot air, so I am confused.

Can anyone shed some light?

Don't think of it as having a heater and an air conditioner. You just tell it what temperature you want. It takes care of the details. It can control both temperature and humidity, and the fresh-air intake, to achieve a comfortable interior environment.

When you select a temperature that is higher than the ambient temperature, it will turn the heater on. But, when the humidity is high, it may also turn the AC on to control the humidity. And it will bring in some outside air to prevent it from becoming stagnant and humid. The result is a comfortable temperature, with little or no window fogging. The humidity is important, because it is a common cause of discomfort, and because it can make the windows fog up.

When you select a temperature that is lower than the ambient, it will still turn the AC on. It may also introduce outside air, if its cool outside. And it will introduce some outside air to keep it fresh.

When the car is really hot, like after being parked in the sun in Florida in the summer, it doesn't automatically open the windows for a minute to let the heat out. But I suppose you can't have everything.

Ah, that makes sense. Thanks!

BTW, I LOL'd at the image of driving down the road and having the windows opening and closing automatically.

That would have been a good scene in Planes, Trains and Automobiles...

Tegster,

In fact, mere humans cannot understand how the TCH climate control system works. Whether or not you are in Auto mode, the AC light occasionally will be on for no apparent reason; the system will arbitrarily decide that you need more air on your feet and change the mode accordingly, regardless of the fact that you selected to have air coming from the upper vents or vice versa; and, at the slightest provocation, it will turn off ECO mode. In other words, the system is "semi-automatic" even with Auto off, and it knows better than you what makes you comfortable -- or so it thinks.

The good news is that the AC light does not necessarily mean that the AC actually is working; it means that it *might* turn on if conditions warrant. And the CC does hold the temperature that you set very nicely, again whether you are in Auto mode or not.

So enjoy it for the 95% of the time that it is doing just what you want. The other 5% will drive you batty if you worry about it!

Bill

The ECO mode and defogging are incompatible. If you change modes to either front defog (separate button) or to windshield/feet, I believe that disables ECO mode. AC will come on to control humidity regardless of mode, as 'needed'.

Assuming you have the CC set to AUTO:
The A/C light merely means the CC system CAN use the A/C if it wants to. It doesn't mean the A/C is actually on. Cold air can be fresh air. Also the CC uses the A/C to control the humidity in the passenger cabin as was posted previously. So if the humidity is high the A/C may be used temporarily to reduce the humidity. This is most common when you use the defrosters and you want DRY air blowing on the windows.

That's correct. My point was that the ECO mode is turned off in a variety of ways: not only any front defrost mode (hitting the FRONT button, deliberately selecting the defrost setting with the MODE button) but also by cycling through the modes (you eventually hit the defrost one) or setting the temperature control to LO or HI.

Bill

Yeah, I wish it would stay "on" but just software disabled for the settings it does not apply so that when you return to a setting it does apply to, it would still be on.

I agree with mikieboyblue on the eco mode switch. I guess I was just used to old cars in that there was a belt that turned the compressor when AC was on, but would also just turn a pulley when it was off so as not to waste gas. My thinking must be outdated, so thank you for the education.

And yes I also agree with the way the system changes the vents around to keep you more comfortable. I never usually mess with the heat and the radio when I get in the car, so this system is like dealing with the most annoying passenger ever. Although I will not name names since she may read this forum ;-)