Initial Inspection and Diagnostic Overview

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

Visual Inspection Chart:

2. Inspect to determine if one of the mechanical or electrical concerns apply.
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 the inspection reveals obvious concerns that can be readily identified, repair as necessary.
5. If the concern remains after the inspection, connect the scan tool to the Data Link Connector (DLC) located beneath the instrument panel and select the vehicle to be tested from the scan tool menu. If the vehicle selection cannot be entered:
- check that the program card is correctly installed.
- check the connections to the vehicle.
- check the ignition switch position.
- check that the battery voltage is greater than 9V.

If the scan tool still does not allow the vehicle selection to be entered, refer to the scan tool manual.

6. Carry out the Data Link Diagnostic Test using the scan tool. If the scan tool responds with:
- CKT 914 and CKT 915 = ALL MODULE NO RESPONSE/NOT EQUIPPED, go to Module Communication Network Diagnostics in 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 Dual Automatic Temperature Control (DATC) module is not listed for a communication concern, execute the self-test diagnostics for the DATC module. Front Panel DATC Module Self-Test (On-Demand DTCs)

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