There are typically two types of air conditioning systems in cars today. One is manual A/C and the other is Automatic Climate Control. A manual system will have fan speed settings and vent selections. These setting can be adjusted manually Only. With an Automatic Climate Control A/C System you can find similar setting along with the ability to select a digital number (ex.65) and an Auto Setting. This will allow the temperature to adjust automatically to keep the cabin at the same temperature by variably changing the speed of the blower motor and the vents.