2006 Chevrolet Impala Question: clicking noise after the ac is turned off!!

Your Blend Door Actuator needs to be replaced. It's a simple fix and fairly inexpensive if you can do it yourself, I purchased the part for less than $40 and we did the replacement our self which took all of 15 minutes. The reson it makes so much noise is that the gears in this part are going bad. I would say replace before winter comes or you may have trouble getting the temp to regulate correctly in your cabin.

This has been going on in my 2006 Impala for the past 2 years, with no damage. My air still runs fine. I hear it once i put the key in the ignition after I automatic start it. It lasted around 50 seconds. Seems longer because it is annoying. It also happens if I switch from outside air(low) to circulating inside air (high), but it also stops after approximately 50 seconds. Me and my dad took out all we could to get to this spinning fan that all mechanics said would be the problem, and it wasn't. We were then told it was some valve on the inside getting stuck, but that no harm would be done by not fixing it. I live in Texas where air is necessary and I have survived without my A/C being affected in a negative manner. Good luck!!

where is the blend door? impala 2006