System description · Heating section

911 Carrera (996) Heating diagnosis System description Heating section The heating system is controlled on the air side, only one button has to be operated here to i.e. coolant continuouslyflows through the heat direct the full heating power to the windows exchanger. The heating is regulated via the in order to ensure rapid defrosting when position of the temperature mixing valve. the vehicle is operated in wintry conditions. Dependingon the position of the temperature A quantity-controlledcompressor produces mixing valve, a certain portion of warmed air the cooling power of the air conditioning. is mixed with the fresh air from the outside. With this demand-dependentquantity control, the compressor makes a contributiontowardsAir-conditioning section energy savings.Whenthe compressor is switched on, only approx. 6 % of the refrigerantThe preselected temperature is controlled quantityis pumped. The start-upjerk that occursautomatically. The interior temperature and with uncontrolled compressors can largelyair flow can be adjusted manuallyvia two be avoided in this way.pushbuttons.The changes are shown in the display. Informationfrom 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 betweenthe upper and lower areas of the passenger compartment to suit the desires of the passengersin most cases. It is neverthelesspossible to control this distribution manuallyby means of the corresponding push buttons. As in other Porsche cars, the air-conditioningsystem of the 911 Carrera (996) is equipped with a "Defrost"button, which ensuresmaximum window defrosting efficiency by suitable control of the heating and blowing power and air distribution. In the interest of simpler use, 80 01 Diagnosis/troubleshooting, heating 80 -D 3 Printed in Germany -11, 1998 99680Dl