Initial Inspection and Diagnostic Overview

1. Verify the customer concern by operating the climate control system to duplicate the condition.

Visual Inspection Chart:

2. Visually inspect for obvious signs of mechanical or electrical damage.
3. As pinpoint tests and measurements are being performed, be sure to inspect for any disconnected, loose fitting, or incorrectly installed component, module and in-line electrical connectors and pins.
4. If an obvious cause for an observed or reported concern is found, correct the cause (if possible) before proceeding to the next step.
5. If the cause is not visually evident, connect a scan tool to the data link connector and select the vehicle to be tested from the scan tool menu. If the scan tool does not communicate with the vehicle:
^ check that the program card is correctly installed.
^ check the connections to the vehicle.
^ check the ignition switch position.

6. If the scan tool still does not communicate with the vehicle, refer to the scan tool operating manual.
7. Carry out the DATA LINK DIAGNOSTICS test. If the scan tool responds with:
^ CKT914, CKT915, or CKT70 ALL ECUS NO RESP/NOT EQUIP, refer to Module Communications Network (Information Bus) to diagnose the network concern.
^ If the Powertrain Control Module (PCM) is not listed for a communication concern, turn the A/C controls to OFF and execute the self-test diagnostics for the PCM.
^ If the EATC module is not listed for a communication concern, execute self-test diagnostics for the EATC module. Electronic Automatic Temperature Control Module Self-Test

8. If any PCM or EATC DTCs are retrieved, and are related to the concern, go to the Powertrain Control Module Diagnostic Trouble Code (DTC) index or the Electronic Automatic Temperature Control (EATC) Module Diagnostic Trouble Code (DTC) index to continue diagnostics. Powertrain Control Module Diagnostic Trouble Code (DTC) Index Electronic A/C Control (EATC) Module Diagnostic Trouble Code
9. If no DTCs related to the concern are retrieved, GO to Symptom Chart to continue diagnostics. Symptom Related Diagnostic Procedures
10. If the EATC module cannot be accessed by the scan tool, GO to Pinpoint Test E. Test E: No Communication W/EATC Module