General HVAC Diagnosis Information

The A/C heater control communicates on the controller area network (CAN) B bus and is fully addressable with a scan tool. Fault detection is through active and stored diagnostic trouble codes (DTCs), which will only display on the scan tool. Active DTCs are those which currently exist in the system. The condition causing the fault must be repaired in order to clear this type of DTC. Stored DTCs are those which occurred in the system since the A/C-heater control received the last clear diagnostic info message. The HVAC System Test, provides a means for diagnosing most stored DTCs. The test consists of four diagnostic procedures, which tests the A/C system performance, mode switches, HVAC system circuits and each actuators door span. Either perform all four tests for a complete system check or perform an individual test if diagnosing a specific symptom. Additional on-board diagnostics include the A/C Cooldown Test, Actuator Calibration function and the Actuator DTC Detection Test.

A/C COOLDOWN TEST

The A/C Cooldown Test:
- is actuated with a scan tool.
- tests A/C system performance based on evaporator temperature sensor input.
- will fail if evaporator temperature is below 18.3° C (65° F) when initiating the test.
- will pass if the evaporator temperature drops 11.1° C (20° F).
- indicates test outcome by displaying one or more test status messages on the scan tool. These messages will clear after paging back out of this test function. Therefore, is it important to note all of the messages before doing so.

- will cause the A/C status indicator to flash while the test is running.

ACTUATOR CALIBRATION FUNCTION

The Actuator Calibration function:
- is actuated with a scan tool.
- homes and repositions door actuators.
- monitors for door span faults. Door span faults XXX Door Travel Range Too Large or XXX Door Travel Range Too Small) will only display after calibration.
- will cause the electric backlight (EBL) status indicator to flash while the test is running.

ACTUATOR DTC DETECTION TEST

The Actuator DTC Detection Test:
- is actuated with a scan tool.
- supplements the continuous diagnostics on the actuator drive system.