System Tests

HVAC SYSTEM TEST
The HVAC System Test, found in HVAC - Electrical Diagnostics, provides a starting point in the diagnostic process by identifying the appropriate diagnostic procedure or system test to perform when diagnosing a given symptom, condition, or DTC. It also provides a means for testing the entire HVAC system by utilizing the A/C-heater control's On-Board System Tests. The On-Board System Tests can also assist in diagnosing stored DTCs.

A/C COOLDOWN TEST
The A/C Cooldown Test:
- is actuated with the DRBIII(R).
- tests A/C system performance based on evaporator temperature sensor input.
- will not run if ambient temperature is below 12.7° C (55° F).
- will pass if the evaporator temperature drops 11.1° C (20° F) within one minute of starting the test.
- indicates an outcome by displaying one or more test status messages on the DRBIII(R). These test status messages will clear after paging back out of this test function. Therefore, is it important to note all of the messages before doing so.

Running the A/C Cooldown Test will cause the A/C status indicator to flash. If the test fails, the A/C status indicator will continue to flash until either the test returns passed or the ignition key is cycled. When the A/C status indicator is flashing, it will not indicate A/C operating status. However, the A/C mode switch will continue to function normally. For vehicles equipped with electric backlight (EBL), when the A/C status indicator is flashing, the EBL status indicator will not function. However, the EBL mode switch will continue to function normally.

HVAC DOOR CALIBRATION
The HVAC Door Recalibration:
- is actuated with the DRBIII(R).
- homes and repositions door actuators
- monitors for door span faults.
- indicates an outcome by displaying one or more messages on the DRBIII(R).

For vehicles equipped with electric backlight (EBL), running the HVAC Door Recalibration will cause the EBL status indicator to flash. If recalibration fails, the EBL status indicator will continue to flash until either the system passes recalibration or the ignition key is cycled. When the EBL status indicator is flashing, it will not indicate EBL operating status. However, the EBL mode switch will continue to function normally. When the EBL status indicator is flashing, the A/C status indicator will not function. However, the A/C mode switch will continue to function normally.

For vehicles not equipped with electric backlight (EBL), no status indicator will flash when running the HVAC Door Recalibration. If recalibration fails, the A/C status indicator will not function, however, the A/C mode switch will continue to function normally.

ACTUATOR CIRCUIT TEST

The Actuator Circuit Test:
- is actuated with the DRBIII(R).
- supplements the continuous diagnostics on the actuator drive system.
- monitors for shorted actuator circuits allowing service to easily diagnose and troubleshoot up to three simultaneous shorts.
- indicates an outcome by displaying up to three messages on the DRBIII(R).

Understanding Actuator Circuit Test Fault Messages
- A Short Too Complex fault message indicates that a specific determination of which lines are shorted could not be made. This fault is caused by more than three drivers being shorted in the same direction (e.g., four drivers all shorted to ground, or two or more drivers shorted with at least one driver shorted to ignition/battery and one driver shorted to ground).
- Fault messages displaying XXX Driver/Circuit Shorted to Ignition/Battery and XXX Driver/Circuit Shorted to Ground will set on a per-driver basis.
- Fault messages displaying the same two drivers/circuits shorted to ignition/battery as-well-as shorted to ground indicates that two actuator driver circuits are shorted together.

When Performing The Actuator Circuit Test
- To ensure a proper diagnosis, repair all Short Too Complex fault messages first, all common door driver circuit related fault messages second, and all other fault messages last.
- After repairing each fault, cycle the ignition switch, then run the Actuator Circuit Test again to ensure that no new faults exist. When the test returns passed, clear all faults and run the HVAC Door Recalibration as a final check of system health.