Climate control units for automobiles come in three basic types that vary according to the amount of control the driver has over the temperature and fan speed. Manual climate control units allow the driver to set exact temperatures and fan speeds, while semi-automatic and fully automatic units have presets that adjust the fan settings to a comfortable level automatically based on the temperature. Many models have windshield defrosters, and some allow different settings for the driver and passengers.
Climate control units have the ability to monitor a car's interior temperature and regulate it based on the user's preferences. To allow the greatest degree of convenience for users, it is best to choose a unit that allows switching between manual and automatic modes. A windshield defroster helps warm up the window to reduce fog and mist, which is useful for drivers in areas with extremely cold winters. Many climate control units have built-in processors that reduce energy consumption to save fuel, and provide just the right amount of heating or cooling to keep the car's interior comfortable. Some units allow heating of the steering wheel, seats and armrests, as well as allowing passengers to adjust the settings of the fan nearest to them.