Initial Inspection and Diagnostic Overview

1. Verify the customer's concern(s) by operating the electronic automatic temperature control to duplicate the condition(s).


2. Inspect to determine if one of the following mechanical or electrical concerns apply:










3. If the concern(s) remains after the inspection, perform the System Self Test using the procedure that follows. Record all DTC's displayed during the self test.

^ The self test can be initiated at any time with any resulting trouble codes. Normal operation of the system stops when self test is activated.

^ To enter self test, position the blower control knob at AUTO and the Function Selector Knob in either PANEL or FLOOR.

^ Then, press and release the COOL and OUTSIDE TEMP buttons simultaneously and, within two seconds, press and release the WARM button. The display will show a tracer segment going in a counterclockwise direction in the center of the display window during the self test.
^ When the self test is completed, DTC's for any fault will be displayed in the VFD Window. If no faults are found, all display segments will illuminate.

^ To exit Self Test and RETAIN all DTC's, press the COOL (BLUE) button.

^ To exit Self Test and CLEAR all DTC's, press the OUTSIDE TEMP button and then, press the WARM button.

^ After exiting the Self Test, the ignition should remain ON for at least 25 seconds to allow the temperature blend door actuator to calibrate.

^ During normal operation, each intermittent trouble code will be deleted after 80 ignition switch cycles.

4. If any Trouble Codes appear during the Self Test, follow the diagnostics procedure given under "ACTION" for each Trouble Code given.

The Self Test will detect faults in the system temperature and blower speed control functions found during the Self Test and will display these codes in addition to intermittent trouble codes for faults that occur during system operation. The vehicle interior temperature must be between 10°C (50°F) and 32°C (90°F) when performing the Self Test. If the temperatures are not within the specified ranges, false in-car temperature sensor trouble codes will be displayed.

5. If no DTCs are generated as a result of the seIf-diagnostic test (88°F°C code is displayed), determine the conditions and go to the Symptom Chart.