If the power steering pump has been replaced, the pulley shaft of the pump is probably out of line. Those shafts have an adjustment on them to help line up the belt. If its out of align then you will get embarrassing squealing noise. It took me a while to figure this out on mine, but that's exactly what was causing the issue.
This chirping has been a problem since we bought the vehicle new. Last year all the pulleys were replaced along with the serpentine belt only to have it start chirping within a month or so. Had the belt replaced in Dec 2013 and it is chirping already, Feb 2, 2014. This is a minor inconvenience in that I could not be happier with this vehicle and it has served my family well.
Belt squeak when air/defroster were used.
Fix was to replace the belt tensioner.
Chirp was miner for 30 to 40 days. I thought it was a pulley on the A/C compressor, which was replaced 8 months ago, or the power stering unit. Just a constant tic tic at idle. It got louder, especially 2000 RPM and up. It got so loud it was embarrassing to drive, but I still thought it had to be a pulley. With a spray bottle I sprayed the ribbed side of the serpentine belt (engine running) with water, the screech even got louder. I read that rubbing a bar of soap on the ribbed side of the belt carefully (while the engine was running) may help, or stop it completely. I put a bar of bath( soap in the jaws of a medium sized pair of Chanel locks and gently pressed the soap against the ribbed side of the belt (engine running) for about 15 seconds, and it worked. Not a single squeak. My wife drove about 60 miles, got home and not a peep. We both are very pleased. Letts hope it lasts. The belt has less than 4000 miles on it. so my concern is what causes this, and do I need to do this proceedure every so many miles?