Belt Squeal - keywords a/c air bolt chirp cold conditioning noise tensioner

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Some customers may comment of a squeal or chirp noise coming from the engine compartment, usually on a cold start. The cause may be the foreign material in the bolt hole for the upper bolt of the air conditioning belt tensioner, not allowing the bolt to achieve full clamp load on the tensioner.

Confirm that the noise is coming from the A/C belt by running the engine with the supercharger belt removed. If the noise is still present, remove the air conditioning belt tensioner, run an M8 X 1.25 tap into the upper bolt hole for the tensioner to clean the threads, and blow out the hole with compressed air. Run the bolt into the hole by hand and make sure that the bolt goes into the hole to the end of the bolt threads. Reinstall the A/C belt tensioner and confirm that the noise is corrected. If the noise is still present, call GM Technical Assistance.

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.