Important: The following steps must be completed before using the symptom tables.
- Perform the 
Diagnostic System Check - Vehicle
 , before using the Symptom Tables in order to verify that all of the following are true:
 
| •  | The control modules can communicate via the serial data link. | 
 
- Review the system operation in order to familiarize yourself with the system functions. Refer to the following information:
 
Visual/Physical Inspection
|     •  | Inspect the easily accessible or visible system components for obvious damage or conditions which could cause the symptom. | 
 
|     •  | Verify the A/C compressor clutch turns freely and is not seized. | 
 
|     •  | Verify that the customer is using the correct key to enable personalization and is not inadvertently activating auxiliary HVAC controls. | 
 
|     •  | The following conditions may cause window fogging: | 
 
|        -  | Blocked A/C evaporator drain tube | 
 
|        -  | Maximum passenger capacity | 
 
|        -  | Blocked body pressure relief valves | 
 
|     •  | Inspect the air distribution system for causes of reduced air flow: | 
 
|        -  | Obstructed or dirty passenger compartment air filter, if equipped | 
 
|        -  | Blocked or damaged air inlet or outlet vents | 
 
Intermittent
Faulty electrical connections or wiring may be the cause of intermittent conditions. Refer to 
Testing for Intermittent Conditions and Poor Connections
 .
Symptom List
Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom: