Climate Control is a more sophisticated control of temperature to what ever is required by the driver or even the passenger independently. Indeed there are now systems which can set four differing temperatures for the four corners of the car. So that the driver may set a required temperature of say, 18ºC and the passenger may prefer 21ºC. The system will then ensure that both are kept to the temperature they require. However the system tries to anticipate your requirement in other little ways - for example if a sensor detects that the sun is shining, it automatically reduces the settings by two degrees to compensate for the extra warming from the sunshine through the glass. Several sensors monitor other factors and compensate as necessary. On the later, more sophisticated systems the AC control module will turn itself on, in demist mode, if sensors have noted that the temperature and relative humidity of the air near the windscreen is likely to cause mist on the screen.
How to cheat with a standard AC system
If you have a simple AC system you can cheat a little and emulate some of the characteristics of Climate Control with just plain old AC.
I'm sure you must have experienced occasions when with the blower for the AC on it's lowest setting giving just a small amount of cold air, the car gradually gets colder and colder and after a short while the car becomes too chilly for comfort. You try turning the AC completely off but in all probability, after a couple of minutes, you will be uncomfortably warm again so that you need to turn the AC on once more.
In these circumstances just pretend you are a Climate Control Module and turn on a tiny amount of heat (with the AC still just turned on – believe me it’s perfectly alright). This combination of a little heat and a little cold should be just what you need – this is all the Climate Control Module is doing for you if you have this. Just adjust the heat control gradually until the temperature is how you like it.
Sometimes I find it helpful to turn the face level vents upwards so they are directing the air over the drivers head and the cold, denser air will fall onto the rear seat passengers. This is particularly useful if these rear passengers are children as they seem to need more cooling than the adults and are thus kept happier.
Similarly when demisting the glassware use a combination of both heat and AC directed at least initially to the front screen but once the relative humity is reduced the direction control can be switched to wherever you require for comfort.