Toyota Repair: high pitched squealing from engine, auto salvage yard, ring pliers

Question
99 Camry 4 door, 4 cyl, automatic, 103k miles
New timing belt and new accessory belts (2).
When ac is turned on (compressor clutch engages), get high pitched squealing.  Have tried to isolate to alternator, but not sure (using a piece of heater hose for this "test").  Have tried adjusting alt/ac belt slightly.  No change.  No starting or charging issues, but if bearings are going on alt, would rather replace now than break down.  Any ideas?  Also, do you know good source of reliable and less expensive than dealer parts?  Just ordered replacement rf window regulator (with) motor from RockAuto.  1/2 of what used parts would have been from auto salvage yard.  Thanks.  This is first car for my kids and I'm trying to keep it running.  Appreciate it.
Rgds/Larry

Answer
Ok, if you remove the belt do you here it, don't worry won't over heat, water pump runs off timing belt and while off not running check the pulley on the A/C, I've known the ider bearing to go out on the commpressor and if it's not to bad you can take the commpressor off and turn it enough to remove the clutch with out dissconnecting the lines and loosing your gas, (take the alt off)(need snap ring pliers) watch for little round shims to come out, you need a 20 thousand clearance on the clutch. If you still here it after taking the belt off it maybe your waterpump, but most of the time this is a rattle when cold. Check this eBay seller for a dang good deal on commpressor with clutch, no core (a9star9a@aol.com)I got one from him for my wifes Honda real nice for the price of 142. to my door. havn't seen know bearings go out in alt on Toyotas yet, stoped charging,$20.00 set of brushes) not bearings