Use the Scan Tool Data Display Values and Definitions Information in order to assist in diagnosing the heater and the A/C control module problems. Compare the vehicles actual scan tool data with the typical data display value table information. Use the data information in order to aid in understanding the nature of the problem when the vehicle does not match with the typical data display values.
The scan tool data values were taken from a known good vehicle under the following conditions:
| • | The ignition switch is in the ON position. |
| • | The engine is running at idle. |
| • | The vehicle is in PARK. |
| • | The doors are closed. |
| • | The windows are closed. |
| • | The ambient air temperatures out of the sun (inside) are at 22-27°C (70-80°F). |
The Outside Air Temperature (OAT) (Range: -40-80°C/-40-176°F)
This data refers to the outside air temperature (C/F) measured at the outside air temperature (OAT) sensor by the heater and A/C control module. In order for this temperature data to update the heater and A/C control module must receive a vehicle speed input via the class 2 serial data line.
The Inside Air Temperature (Range: -40-80°C/-40-176°F)
This data refers to the inside air temperature (C/F) measured at the inside air temperature sensor by the heater and the A/C control module.
The A/C (Upper) Outlet Temperature (Range: -40-80°C/-40-176°F)
This data refers to the discharged air temperature at the upper outlet.
The Heater (Lower) Outlet Temperature (Range: -40-80°C/-40-176°F)
This data refers to the discharged air temperature at the lower outlet.
The Solar Load Sensor (Range: 0-255 Counts)
This data refers to the amount of the heat load generated by the sunlight measured by the solar load sensor. If the sunlight heat load is high the display will show 100-200. Approximately 230 counts are displayed when the sunlight heat load is minimum.
The Mix Valve Position (Range: 0-256 Counts)
This data refers to the maximum position of the air mix valve.
The Air Mix Valve Commanded (Range: 0-256 Counts)
This data refers to the commanded air mix valve position driven by the heater and the A/C control module.
The Air Mix Actual (Range: 0-256 Counts)
This data refers to the actual air mix valve position monitored via the feedback line (CKT 733) to the heater and the A/C control module.
The Mix Valve Minimum Position (Range: 0-256 Counts)
This data refers to the minimum position.
The Blower Motor PWM Speed (Range: 0-100%)
This data refers to the blower motor fan speed. Zero (0) is displayed when the blower motor is OFF. The blower motor at the maximum speed will display 96-99%.
The Mode Selection Position Upper (Display: Auto/Upper Outlet/Bi-Level/Floor/Defog/Defrost)
This data refers to the position of the mode selection knob and the direction of the discharge air flow through the floor, instrument panel and windshield defroster outlet vents. The positions are displayed as follows:
| • | AUTO -- The heater and the A/C control module control the discharge of air flow through the heater and A/C control system. |
| • | UPPER OUTLET -- The air is flowing out the 4 upper outlets. |
| • | BI-LEVEL -- The air is flowing out the 4 panel vents and the 2 floor vents. |
| • | FLOOR -- The air is flowing out the 2 floor vents. |
| • | DEFOG -- The air is flowing out the defrost vent at the top of the instrument panel. |
| • | DEFROST -- The air is flowing out the defrost vent at the top of the instrument panel. |
The A/C Request (Display: Yes/No)
This data refers to the operation of the A/C compressor clutch message from the heater and the A/C control module to the VCM. The scan tool sends a message to the VCM in order to turn the A/C compressor clutch. This message does not affect the state of the A/C LED on the heater and A/C control.
The A/C LED On (Display: On/Off)
This data refers to the illumination of the A/C push button switch LED (Light Emitting Diode). The LED is mounted in the A/C push-button switch is ON when the A/C push-button is pressed indicating that the air conditioning is being requested. Pressing the A/C push-button while the LED is ON will turn the LED OFF and signal the heater and A/C control that the air conditioning is not requested.
The Rear Defogger Switch (Display: On/Off)
This data refers to the illumination of the rear defogger push-button switch LED. The LED mounted in the rear defogger switch is ON when the rear defogger button is pressed in order to indicate that the rear defogger is being requested. Pressing the rear defogger push-button while the LED is ON will turn the LED OFF and signal the heater and A/C control that the rear defogger is not requested.
The Select Solenoid 1 (Display: ON/OFF)
This data refers to the heater/defrost vacuum select solenoid in the heater and A/C control solenoid assembly.
The Select Solenoid 2 (Display: ON/OFF)
This data refers to the A/C vacuum select solenoid in the heater and A/C control solenoid assembly.
The Select Solenoid 3 (Display: ON/OFF)
This data refers to the heater vacuum select solenoid in the heater and A/C control solenoid assembly.
The Select Solenoid 4 (Display: ON/OFF)
This data refers to the defrost vacuum select solenoid in the heater and A/C control solenoid assembly.
The Select Solenoid 5 (Display: ON/OFF)
This data refers to the air inlet select solenoid in the heater and A/C control solenoid assembly.
