The HVAC control module monitors the ambient light on the vehicle via light
sensitive photodiode, which is called a solar load sensor. The HVAC control module
uses this information in order to compensate for the effect of the sun on the inside
air temperature of the vehicle. When the sensor is in direct sunlight, the ambient
light counts are low. When the sensor is shaded, the ambient light counts are high.
The HVAC control module requests engagement of the A/C compressor clutch, and controls
the door position of the air temperature actuator in order to maintain the selected
air temperature on the HVAC control module.
DTC Parameters
Important: The vehicle must be outside for the photodiode to receive proper lighting. Fluorescent
lighting will not work.
| • | The ignition is in the RUN position. |
| • | LT BLU/BLK (Circuit 590) is shorted to ground. |
| • | The condition is present for 60 seconds. |
| • | The counts are less than 6. |
Diagnostic Aids
| • | If DTC in history or an intermittent condition, perform the test shown
by wiggling wiring and connectors. This will cause malfunction to appear. |
| • | Visually inspect sensor connector and harness for damage, corrosion or
water intrusion. |
| • | Inspect connector halves for poor mating or terminal not fully seated
in the connector body (backed out). |
| • | Inspect for adequate terminal tension, mis-routed harness, rubbed-through
wire insulation and broken wire inside the insulation. |
| • | Inspect for improperly formed or damaged terminals. All connector terminals
in the related circuit should be carefully reformed or replaced to ensure proper contact
tension. |
