No matter how tight I make the belts on my factory ac compressor it the belt shakes up and down and slips on the compressor. Once I bring the RPMs op to about 2000 it's fine any ideas or photos of the belt assembly. Unlikely but wondering if an idler puppy or something is missing. Any help Appreciated

Them idler puppies aren't properly trained. Some newspaper will help that. Roll it up tight and smack it a good one when it acts up, it'll learn.

In all seriousness, belts come in a couple of widths, wrong width, usually too narrow, won't work right, it doesn't grip properly. It the belts a bit too long it won't tighten up right. If it's the cheapest belt at the Zone, it's probably crap off the shelf.

You don't give a make/model/engine/etc info so it's hard to say but surf Rockauto and see if the numbers there match your belt.

They used to sell those belts for th AC in matched pairs. They were cut from the same bulk core so the were exactly the same size. I got lucky and bought ones from O'riellys and they had the same batch number so they tightened up fine.

bad belt. worn side grooves in pulley. missing idler pulley. improper alignment (maybe). too long of belt (something not positioned right as in mismatched parts-pulleys too far away from each other. Just throwin some potentials out there

I agree with making sure the width is correct. I ran into that a few years ago. If the belt is too narrow it will sit too low and slip.

Gates shows the belt to be 13/32" wide, Dayco shows it to be 15/32" wide.

I'd go with Dayco myself.

Even with brand new matched pair belts, the belt wobble is normal....the belts simply span too much length without support. In the later years the factory added an idler pulley to bear on the top of the belts between the compressor and the alternator to lessen the wobble.

When the 2 cylinder compressor is operating the belts normally jump due to the load pulses... but should not jump to the extent they slip.

Agree make sure the belts are wide enough and reasonably well matched. hopefully that clears it up.