2006 Chevy Impala scan codes B0223, B0408, B0418 with loud ratcheting noise under center dash when temp selected full cold.
The body computer codes are an indication of a problem with the circuits that maintain your a/c system & is most likely a failed actuator.This is the noise you hear ,the actuators internal plastic gears have failed.The circuit/system description is :
The HVAC control module controls the HVAC door actuators to regulate the airflow through the HVAC system. Each actuator consists of two driver circuits. The HVAC control module supplies the actuator motor with a 12-volt driver control circuit and a ground driver control circuit. The HVAC module controls the direction of the actuator door by changing the polarity of the control circuits.
A.S.E MasterTechnician A1-A8 w/L1,38 years experience General Motors Master Technician
Good answer. Are these actuators fairly easy to change, and if so, where are they located?
To replace the mode actuator( which is in the center of the dash) the instriment panel compartment inner panel must be removed.Here is some help.
Instrument Panel Compartment Inner Panel Screws (Qty 7)
Tighten2 N·m (18 lb in)
Instrument Panel Compartment Inner Panel Assembly
TipFlex the bottom right hand corner of the Instrument Panel in order to remove the Instrument Panel Compartment Inner Panel Assembly.
Mode Actuator Screw (Qty: 2)
Tighten1.5 N·m (13 lb in)