System Description

Heating section
The heating system is controlled on the air side, i.e. coolant continuously flows through the heat exchanger. The heating is regulated via the position of the temperature mixing valve.
Depending on the position of the temperature mixing valve, a certain portion of warmed air is mixed with the fresh air from the outside.

Air-conditioning section
The preselected temperature is controlled automatically. The interior temperature and air flow can be adjusted manually via two push-buttons. The changes are shown in the display. Information from the outside temperature sensors, interior temperature sensor and the sun sensor is processed to regulate the interior temperature. The system can respond to rapid changes in the outside temperature and also takes into account that the intensity of sunlight has a major influence on the subjective temperature perception of passengers.

The fully automatic control system influences the temperature distribution between the upper and lower areas of the passenger compartment to suit the desires of the passengers in most cases. It is nevertheless possible to control this distribution manually by means of the corresponding push buttons. As in other Porsche cars, the air-conditioning system of the 911 Carrera (996) is equipped with a 'Defrost' button, which ensures maximum window defrosting efficiency by suitable control of the heating and blowing power and air distribution. In the interest of simpler use, only one button has to be operated here to direct the full heating power to the windows in order to ensure rapid defrosting when the vehicle is operated in wintry conditions.

A quantity-controlled compressor produces the cooling power of the air conditioning.
With this demand-dependent quantity control, the compressor makes a contribution towards energy savings. When the compressor is switched on, only approx. 6 % of the refrigerant quantity is pumped. The start-up jerk that occurs with uncontrolled compressors can largely be avoided in this way.