very light whirring (fan?) sound from second row headliner area

[pennyanguy]

New (1 month) to us 2003 Tahoe LT with EVERY bell and whistle.. just noticed today a very light whirring (fan?) sound from second row headliner area ... I only noticed it when the key was on but the truck not running. I checked all the HVAC controls, everything was shut down. Sound definitely coming from the headliner ceiling area and winds down to nothing when key is shut off... Is there some type of a vent fan in the ceiling?

 

[Roilux]

New (1 month) to us 2003 Tahoe LT with EVERY bell and whistle.. just noticed today a very light whirring (fan?) sound from second row headliner area ... I only noticed it when the key was on but the truck not running. I checked all the HVAC controls, everything was shut down. Sound definitely coming from the headliner ceiling area and winds down to nothing when key is shut off... Is there some type of a vent fan in the ceiling?

It's probably the rear aspirator. The front aspirator is located in the headliner above the driver's seat. They are the temperature measuring component of your climate control system. Here's a thread chatting about them and a write up I did on how to replace the rear unit on page three. Replacing the front unit is mentioned earlier in the thread. https://www.tahoeyukonforum.com/thr...-of-denali-making-a-humming-noise.4859/page-3

It's best not to skimp on this part and buy Genuine GM # 22834330 Cabin Air Temperature Sensor Aspirator