SENSOR-SUN
DESCRIPTION
The automatic temperature control (ATC) heating-A/C system uses a sun sensor assembly (1) to measure sun light intensity. The sun sensor assembly incorporates two sun sensors (2) within a molded plastic case which is mounted to the instrument panel and a clear lens (3) that protrudes through the defroster grille. The wire harness receptacle (4) connects the sun sensors to the vehicle electrical system through a wire lead and connector of the instrument panel wire harness.
OPERATION
The ATC heating-A/C system uses two sun sensors to balance the system in response to side-to-side variations in sun light intensity. Passengers in sun and shadow require different functional settings because they experience very different temperatures. The sun sensor assembly provides data to the A/C heater control to help determine proper mode and blend-air door positions and blower motor speeds. The sun sensors are not thermistor type sensors, but rather photo diodes. For this reason the sun sensors responds to sun light intensity rather than temperature. The sun sensor assembly is also used to sense day and night conditions for automatic headlight control on MTC equipped vehicles.
The sun sensor is diagnosed using a scan tool (refer to 24 - HEATING & AIR CONDITIONING - DIAGNOSIS AND TESTING - HEATING AND A/C SYSTEMS and to 24 - HVAC Electrical Diagnostics for more information).
The sun sensor assembly cannot be adjusted or repaired and must be replaced if found inoperative or damaged.
REMOVAL
WARNING: Disable the airbag system before attempting any steering wheel, steering column, or instrument panel component diagnosis or service. Disconnect and isolate the negative battery (ground) cable, then wait two minutes for the airbag system capacitor to discharge before performing further diagnosis or service. This is the only sure way to disable the airbag system. Failure to take the proper precautions could result in an accidental airbag deployment and possible personal injury or death.
1. Disconnect and isolate the negative battery cable.
2. Using trim stick C-4755 or equivalent (1), gently pry between both sides of the sun sensor (2) and the instrument panel (3) to release the snap clip retainers located at the front of the sensor near the windshield.
3. Carefully pull the sun sensor (2) partially out of the instrument panel (3) and disconnect the wire harness connector (1) from the sensor.
4. Remove the sun sensor from the vehicle.
INSTALLATION
1. Position the sun sensor (2) near the instrument panel (3).
2. Connect the wiring harness connector (1) to the sun sensor.
3. Align the tab on the sun sensor with the opening in the instrument panel and install the sensor onto the instrument panel. Make sure that the sensor's retaining clips located at the front of the sensor near the windshield are fully engaged to the instrument panel.
4. Reconnect the negative battery cable.