#PIT3511D: Buzz Or Hum Noise From Headliner Above Driver - (Jun 1, 2011)
Subject: Buzz or Hum Noise From Headliner Above Driver
Models: 2002-2011 Cadillac Escalade, EXT, ESV
2000-2011 Chevrolet Avalanche, Suburban, Tahoe
2003-2011 Chevrolet Silverado, Silverado Classic
2003-2011 GMC Sierra, Sierra Classic
2000-2011 GMC Yukon, Yukon XL, Yukon Denali, Yukon Denali XL With RPO CJ2 or C68
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This PI was superseded to update model years. Please discard PIT3511C.
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The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
Condition/Concern:
Customers may comment that they have a buzz/vibration/hum noise emanating from the headliner in an area that looks like a microphone or a small speaker.
Recommendation/Instructions:
The plastic escutcheon grill, which is round and located just above the driver, is the inside air temperature sensor. The sensor is used in conjunction with the automatic HVAC. On occasions, this sensor has been known to make a buzz/vibration/hum sound. The sensor uses a small fan to pull air over the sensor. This noise may be intermittent.
Although it may not be possible to alleviate all of the noise, Engineering has found that if the sensor is installed incorrectly that it may bind and cause the fan to make noise. Remove the sensor and while doing so check for any binding. Reinstall the sensor and retest. If the noise is still present, the sensor itself may be noisy and require replacement.
Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.