Automatic Climate Control: Overview — Saab 9-5 I рестайлинг 2 (2005-2010)

Automatic Climate Control: Overview Saab 9-5 I рестайлинг 2

Brief Description

The main purpose of the ACC system is to control the climate unit in order to achieve comfortable climate conditions as soon as possible after starting the car and then to maintain them. The ACC unit consists of a control panel with knobs and buttons as well as an integrated control module. Under normal conditions, the control module automatically controls the following functions

Description of operation

The ACC unit supplies the heating element with a B+ voltage from K2 pin 1 which is then grounded via G 14. The heating element in the passenger seat is supplied with a B+ voltage from K2 pin 6 and is grounded via G 24.

The temperature sensor (254) is grounded internally in the ACC unit via K1 pin 23 for both driver's seat and passenger seat

The driver's seat sensor is supplied from K2 pin 4 with 5V via a 6.8 Kohms resistor built into the ACC unit. The characteristics of the NTC resistor mean that resistance decreases afterwards as the temperature increases. This means that the voltage measured over the resistor will at the same time decrease during rising temperatures.

The passenger seat sensor is supplied from K2 pin 5 with 5V via a 6.8 Kohms resistor built into the ACC unit. The characteristics of the NTC resistor mean that resistance decreases afterwards as the temperature increases. This means that the voltage measured over the resistor will at the same time decrease during rising temperatures.

The voltage value from the sensor is A/D converted and is then available in digital form. The digital voltage value is then converted to temperature and is added to the ACC unit's operating memory. Voltage values close to 0 or 5V are interpreted as faults in the circuit.

The fans in the ventilated seats are controlled manually with pushbuttons in the ACC panel. The LEDs in the buttons show fan speed. The preconditions are that the engine is running and that the cabin fan knob is not in the OFF position.

The fan speed in the driver's seat and passenger seat is controlled by a voltage

Step 1: low speed approx. 9.3 volts

Step 2 : high speed approx. 11 volts

The ACC unit's K1 pin 2 is connected to the driver's seat fan and is grounded via G14 and K1 pin 11 to the passenger seat's fan that is grounded via G24.