Important: Complete the following steps before using the symptom tables:

1. Perform Diagnostic System Check - HVAC Systems - Automatic before using the Symptom Tables in order to verify that all of the following conditions are true:

1.1.	No DTCs are set.

1.2.	The control modules can communicate via the serial data link.

2. Review the system operation in order to become familiar with the system functions. Refer to the following procedures:

•	Air Delivery Description and Operation

•	Air Temperature Description and Operation

1. Inspect for aftermarket devices which can affect the operation of the HVAC System. Refer to Checking Aftermarket Accessories in Wiring Systems.
2. Inspect the accessible and the visible system components for obvious damage or for conditions which can cause the symptom.
3. Verify the A/C compressor clutch turns freely and is not seized.
4. Verify that the customer is using the correct key in order to enable personalization and is not activating the auxiliary HVAC controls.
5. The A/C compressor will not operate in cold ambient air temperatures. Refer to Air Temperature Description and Operation .
6. The following conditions may cause window fogging:

-	A wet carpet or wet floor mats

-	High humidity

-	An interior water leak

-	A blocked A/C evaporator drain tube

-	Maximum passenger capacity

-	Blocked body pressure relief valves

7. Inspect the air distribution system for causes of reduced airflow:

•	An obstructed or dirty passenger compartment air filter, if equipped

•	Blocked or damaged air vents

Faulty electrical connections or wiring may be the cause of intermittent conditions. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Refer to the following diagnostic procedures: