Toyota Repair: odor in vent system, cabin air filter, vent fan

Question
QUESTION: I have a 2011 Camray. Upon starting the engine and turning on the vent fan there is a terrible odor [mold/dust] It only lasts about 30 seconds. The dealer finally agreed to check it out and then when you turn on the vent fan it smelled like they had stuck a cardboard deodorizer into the vent system. After 1 month it is back to smelling like dust etc...

ANSWER: This model has a cabin air filter located behind the glove box, did they replace it if not then this needs to be done.

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QUESTION: The cabin air filter was also cleaned but did not help the odor.

Answer
A couple of suggestions for you to try, don't use the recirc setting, leave it on fresh air, check the a/c evaporator drain to make sure it is draining condensation outside the car underneath, you can check the hose by pulling back the passenger fllor carpet, you will see the drain hose, pull the hose off the evaporator and see if any water drains out. If it does the drain tube is blocked.