Whenever I try to loosen/tighten the 14mm, the tensioner spins (the belt doesn't). Any idea how I loosen this? I'm trying to get access to the shim so I can measure the gap. On startup, the ac clutch doesn't engage but when I gently whack it with a mallet, it starts working (read up on here that I just need to replace the shim).
Any input is greatly appreciated, I'm desperately trying to get my AC blowing cold again. Thanks!!

You need an impact gun

you can get a flat screw driver and hold it through the triangle part to lock it in place and then try to loosen the nut.

The clutch gap is measured with the clutch mounted on the compressor.

Thanks, didn't know that. But I'll still need to get that 14mm off to adjust the gap as its certainly not to spec

Thank you, could you be a bit more specific?

Either an impact gun, or most auto parts store rent the AC clutch tool set.

Factory spec for the nut is 12 ft/lbs. I remember just holding the front plate with my hand when loosening the nut. So, if someone hasn't horsed it on, it should be easy to remove.

I'll give the impact gun a go, thanks!

Yeah I tried that, as well as using the handle of a hammer to try and wedge it while loosening, its definitely on there pretty good . I'll do what the others mentioned and give it a go with an impact wrench. Thanks for the input!