I have a twenty year old Toyota pickup that makes one loud squeal within the first couple of minutes after the a/c is turned on. It lasts maybe five-ten seconds. It usually only happens once in a day. It stops immediately when the a/c is turned off.
I’m trying to get an idea of what it might be before I take it to a shop.
It MIGHT be an old belt that needs to be replaced.
It’s probably a slipping drive belt. Check the tension on the AC drive belt. It may be time for a new belt.
It’s probably a bad drive belt. There is a fairly new belt out called the Goodyear “Gatorback” and I hear a lot of good things about it. It’s in the 15-20 dollar range so it’s not cheap but it’s not expensive either.