GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2006 🢒 STS 🢒 HVAC 🢒 HVAC Systems - Automatic 🢒 Symptoms - HVAC Systems - Automatic

Important: The following steps must be completed before using the symptom tables.

  1. Perform the Diagnostic System Check - Vehicle , before using the Symptom Tables in order to verify that all of the following are true:
    2. • There are no DTCs set.
    • The control modules can communicate via the serial data link.
  2. Review the system operation in order to familiarize yourself with the system functions. Refer to the following information:
    3. •  Air Delivery Description and Operation
    •  Air Temperature Description and Operation

Visual/Physical Inspection
    • Inspect for aftermarket devices which could affect the operation of the HVAC System. Refer to Checking Aftermarket Accessories .
    • 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 A/C compressor will not operate in cold outside air temperatures. Refer to Air Temperature Description and Operation .
    • The following conditions may cause window fogging:
       - Wet carpet or mats
       - High humidity
       - Interior water leak
       - 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:

    •  HVAC Compressor Clutch Does Not Engage
    •  HVAC Compressor Clutch Does Not Disengage
    •  Blower Motor Malfunction
    •  Too Hot in Vehicle
    •  Too Cold in Vehicle
    •  Air Delivery Improper
    •  Air Recirculation Malfunction
    •  Leak Testing in Heating, Ventilation and Air Conditioning
    •  Noise Diagnosis - Blower Motor in Heating, Ventilation and Air Conditioning
    •  Noise Diagnosis - Air Conditioning (A/C) System in Heating, Ventilation and Air Conditioning
    •  Odor Diagnosis in Heating, Ventilation and Air Conditioning
    •  Steering Wheel Controls Inoperative