I can’t for the life of me figure out this tensioner on the AC. I don’t have the screw on the back of the idler pulley like I keep seeing. Can someone tell me if this is a different type of set up or what. The only bolt I thought might release tensioner is a big 18mm that won’t budge.

 

My guess is the bolt on the backside of the pulley mount secures the position. The front bolt just holds the pulley to the bracket. The bracket has a 'squared' shaft that look like it is meant to take an open end wrench for leverage to tighten the belt. Then at the same time you tighten the backside bolt to hold the pulley in place.