Q: Bad smell in AC vent

Hi there. This is a concern I have had a lot of experience with. Has the AC drain grommet been updated or removed? The original grommet was designed with a small slit style opening and was found to not be sufficient in draining moisture from the evaporator. There would be a build up of mildew that prevented proper drainage thus resulting in Lexus authorizing the removal/replacement of those grommets under a limited bulletin.

If the grommet is not the issue, then moisture buildup inside the evaporator case is the issue. Toyota Motor Company released a tech tip to the dealerships that describes how to reduce the smell and I’ll give you the short version here: during the last 5 to 10 minutes of your drive set the climate control to max fan, fresh air, max cold, no AC, and leave the fresh air setting on when shutting off the vehicle.

This setting allows mass amounts of fresh air to dry the evaporator and case to the point where mold and mildew cannot thrive and leaving the fresh air setting on will allow the evaporator case to breathe and dry out. You may have to do this several times to help with the smell or an AC refresh service available at most service centers may be necessary if the smell is pretty substantial right now. Once the smell is gone, you may only need to do the tech tip once in a while as long as you make sure the fresh air setting is on when you turn off the vehicle. Your mechanic has several technicians available to inspect the air conditioner system and move forward with repairs.