Sunlight Sensor

Sunlight Sensor

The sunlight sensor consists of a LH and a RH photoelectric cell that provide the ATC ECU with inputs of light intensity. These are used by the ATC to adjust blower speed, temperature, and air distribution. The ATC ECU (C1629) provides a feed to the sunlight sensor (C0790) on a YB wire. The LH photoelectric cell (C0790) returns a signal back to the ATC ECU (C1629) on a YR wire. The RH photoelectric cell (C0790) returns a signal back to the ATC ECU (C1629) on a YG wire. The ATC ECU (C1629) provides an earth path for the sensor (C0790) on a YN wire.

Pollution Sensor

The pollution sensor allows the ATC ECU to monitor the ambient air for the level of hydrocarbons and oxidized gases. The ATC (C1629) provides two feeds to the sensor (C1548). The first is on a U wire, and is used to heat the sensor. A second feed is provided on a Y wire. This is a 5 V reference voltage to the sensor itself. A signal voltage of between 0 V and 5 V is returned from pin 3 of the sensor (C1548) to the ATC ECU (C1629) on an N wire. The ATC ECU (C1629) provides an earth path for the sensor (C1548) on a second N wire (pin 1 of the sensor connector).

Front Blower Motor

Operation of the front blower motor is controlled by the ATC ECU via the front blower motor control unit. To control front blower motor speed, the ATC ECU (C0923) provides a stepped voltage of between 0 V and 8 V to the control unit (C2281) on a UR wire. This is used by the control unit to regulate the supply voltage from maxi fuse 64 of the passenger compartment fuse box to the front blower motor (C0056) on BG and RG wires.

The front blower motor control unit (C2281) is earthed on an N wire.

Rear Blower Motor

Operation of the rear blower motor is controlled by the ATC ECU via the rear blower motor control unit. The ATC ECU (C0923) receives an input voltage of between 1.25 V (blower off) and 5 V (maximum blower speed) from the rear blower motor thumbwheel (C0846) on an RB wire. The thumbwheel is a potentiometer located in the rear ATC control unit. The ATC ECU (C0923) determines the blower speed requested from the voltage received from the thumbwheel and provides a stepped voltage of between 0 V and 5 V to the control unit (C2282) on a B then R wire. This is used by the control unit to regulate the supply voltage from the rear blower relay (C2021) to the rear blower motor (C2279) on GY and N wires.

The rear blower motor control unit (C2282) is earthed on an N wire.