Initial Inspection and Diagnostic Overview

1. Verify the customer's concern by operating the climate control system to duplicate the condition.
2. Inspect to determine if one of the following mechanical or electrical concerns apply:







VISUAL INSPECTION CHART

[a]: A leak in the vacuum control circuit may occur during acceleration (slow leak), may exist at all times (large leak), and may exist only when specific functions are selected (indicating a leak in that portion of the circuit). The vacuum hoses used in the passenger compartment control circuit are constructed from PVC plastic material. The vacuum hoses used in the engine compartment are constructed of Hytrel(R). Because of the materials used, never pinch the vacuum hoses off during diagnosis to locate a leak. A wood golf tee can be used as a plug when it is necessary to plug one end of the vacuum hose for leak test purposes.

3. If the inspection reveals obvious concern(s) that can be readily identified, service as required.
4. If the concern remains after the inspection, connect a 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.
5. If the scan tool still does not allow the vehicle selection to be entered, refer to the manual of the scan tool.
6. Perform the DATA LINK DIAGNOSTIC TEST using the scan tool. If the scan tool responds with:
^ CKT914 and CKT915 = ALL MODULE NO RESPONSE/NOT EQUIPPED, go to Module Communications Network (Information Bus) to diagnose the network communication concern.
^ If the powertrain control module (PCM) is not listed for a communication concern, turn the A/C controls off and execute self-test diagnostics for the PCM.
^ If equipped with the EATC, and the EATC module is not listed for a communication concern, execute self-test diagnostics for the EATC module. On-Demand Self-Test
7. 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 or Electronic Automatic Temperature Control (EATC) Module Diagnostic Trouble Code (DTC) Index
8. If no DTCs related to the concern are retrieved, go to the Symptom Chart to continue diagnostics. Symptom Related Diagnostic Procedures
9. If the EATC module cannot be accessed by the scan tool, go to Pinpoint Test E. Test E: No Communication With the Electronic Automatic Temperature Control Module