2000 Jeep cherokee sport

I recently repaired my ac by replacing the evaporator. The jeep starts and runs fine. Cold air blows when switched on. My problem here is that for the first 45 to 60 seconds after I start the vehicle and put on the ac there is an extremely loud high-pitched squealing noise that sounds a hundred times worse than nails across a chalk board. After that first minute or so the noise goes away and it runs fine. I'm figuring that something needs to be oiled, lubricated, etc. Thanks for any help or advice. Phil

phil , just had the same problem sounds like your belt is too tight or your whole AC unit is siezed up

It is probably the belt squeeling.

Either too loose or the system is over charged-most likely. if it was the compressor bearing the noise wouldn't quit like you describe.

JD