My car’s engine began to make a high-pitched squealing noise at times, and I tracked it down to the idler pulley for the AC compressor belt.
To replace the pulley required a bit of flexibility and squeezing in tight spots. I had to remove the power steering belt and pump from its bracket and move it out of the way, then used an extra long ratcheting 14mm wrench to remove the nut from the pulley.
This is the tensioner assembly that the idler pulley rides on. I had to unbolt it because I also bought a new bolt for the pulley to go on. When tensioning the belt you loosing the not and screw the long bolt in or out to tension the belt. The tensioner is held on by two bolts.
The old pulley next to the new pulley. The new one spins freely, while the old one has a lot of resistance and notchiness.