The following are instructions on how to replace the aspirator that is a part of the auto climate control system on my 2001 Tahoe. The aspirator consists of a small fan and a temperature sensor that feed information back to the main controls to let them know what the air temp near the driver's side ceiling is. The reason I needed to replace this was that the fan within the sensor was beginning to fail and make random buzzing sounds that were enough to drive me crazy. Often a little compressed air can clean the blades off to reduce the buzzing but in this instance, the dirt was not the problem, the fan was simply going bad. The first step was to locate the aspirator's grill . The next step was to remove the grill by prying it off with a small flat-head screw driver. There are four clips that hold it in place. Once the grill has been removed the next step is to remove the driver's side sun visor and pull back the A-pillar cover. Once the visor and pillar cover are out of the way the headliner needs to be flexed down to allow access to the aspirator itself. The last step is to remove the old aspirator and replace it with the new. This is what the back of the part look slike and where the harness plugs in. Once the aspirator has been replaced, work in reverse to finish up! This takes all of about 10 minutes to complete. The part costs about $45. The part number is 25903301.