A/C Blower runs eratiacally.

I just recently resolved this problem on my 08 Tahoe LT. There are a number of places that you can look and since you've already checked the fuses, the common problems are in with the blower control module (often referred to as the blower resister) and the blower motor itself. The module is roughly $30 USD and the blower motor is $80 - $90 USD. Both are relatively easy to replace. I replaced both but the culprit was the motor, the bearings have likely worn and the fan cage simply seizes up. The total repair time was about 30 minutes. Two 7mm screws hold the cover in place and an additional two 7mm screws secure the control module to the assembly frame. The motor is "locked" in place with a tab that you pull down and rotate the motor assembly clockwise (from above) and it will drop down into your hand. Replace and restore. Quick and easy. Good luck.