Hmmm... I get that squeal too. I thought it was the P/S too. I was working on my friend's mom's Miata last week... new radiator, upper & lower hoses & replaced belts. When I was leaving it was late & humid and my car squealed for a few secs and her mom's B/F was outside and heard it and said it sounded like the A/C to him.
Tighten the belts, spray them clean with some non chlorinated brake clean spray and then use spray silicon on them should stop all squealing