Hi Mayhem and welcome.
Your description of clicking like a worn cam makes me think it’s not directly AC related, but more info is needed to narrow it down.
Can you hear the click inside, outside or both?
If inside only, it could be a plastic gear jumping teeth on one of the flaps in the air system. If it still does it with the AC off but the fan running it could be debris inside the fan housing. If outside only, and it doesn’t do it with the AC off it is most likely to do with the AC system itself. See if you can pinpoint exactly where the click is coming from.
Completely unrelated is the steering adjustment motors start to have gear jumping issues. If it still does it with the AC and fan off, then it could be this that’s causing the clicking.
Any of the above could increase slightly with engine speed lifting off idle as the charge voltage rises to the battery.
I’m not sure on the 100 series but the 80s have a sight glass on the thinner pipe returning to the cabin AC evaporator. If this has bubbles in it for long periods then it needs gas. If it’s clear it’s either full or empty.