What is the clicking noise under side dash on a 2003 Chevy Silverado?

The clicking noise underneath the dash may be coming from the blend door actuator, that adjusts airflow to the vents in the dash. These actuators are a common failure on the 2003 Silverado. Sometimes the clicking noise can be due to a loose or broken mounting screw of the actuator. You may be able resolve this by tighten the screws that mount the actuator to the housing or replace the actuator.

Here's a general guideline on how to access and check the actuator:

1. Park the vehicle and turn off the engine.

2. Locate the blend door actuator. It's usually found underneath the dashboard on the passenger side.

3. Remove any covers or panels that may be blocking access to the actuator.

4. Inspect the actuator for any signs of damage or loose parts.

5. Try moving the actuator manually to see if it feels smooth or if there's any resistance.

If the actuator is damaged or stuck, you may need to replace it. Here's a general overview of the steps involved in replacing the blend door actuator:

1. Disconnect the negative battery cable to prevent any electrical accidents.

2. Locate the blend door actuator.

3. Disconnect the electrical connector from the actuator.

4. Remove the mounting screws that secure the actuator to the housing.

5. Remove the old actuator from the vehicle.

6. Install the new actuator by reversing the removal procedure.

7. Reconnect the electrical connector to the actuator.

8. Reconnect the negative battery cable.

9. Test the blend door actuator to make sure it's working properly.

If the clicking noise persists, it's recommended to consult a qualified mechanic for further diagnosis and repair.