Initial Inspection and Diagnostic Overview

1. Verify the customer's concern by operating the climate control system to duplicate the condition.
2. Visually inspect for obvious signs of mechanical or electrical damage.

Visual Inspection Chart:

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 an obvious cause for an observed or reported concern is found, correct the cause (if possible) before proceeding to the next step.
4. If the cause is not visually evident, connect the diagnostic tool to the Data Link Connector (DLC) and select the vehicle to be tested from the diagnostic tool menu. If the diagnostic 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.
5. If the diagnostic tool still does not communicate with the vehicle, refer to the diagnostic tool operating manual.
6. Carry out the DATA LINK DIAGNOSTICS test. If the diagnostic tool responds with:
- CKT 914 or CKT 915 = ALL ECUS NO RESP/NOT EQUIP, refer to Module Communication Network (Information Bus).
- SYSTEM PASSED, retrieve and record continuous diagnostic trouble codes (DTCs), erase the continuous DTCs, and carry out the self-test diagnostics for the EATC module. Electronic Automatic Temperature Control Module Self-Test
- If the electronic automatic temperature control module cannot be accessed by the diagnostic tool, GO to PINPOINT TEST E. Test E: No Communication With the Electronic Automatic Temperature Control Module
7. If the DTCs retrieved 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. 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, proceed to the Symptom Chart. Symptom Related Diagnostic Procedures