What's that popping noise?

I have a 2002 Ford Explorer XLT (4 wheel drive). My car makes a popping noise that is also sometimes accompanied by a squealing noise under the following conditions.



1) turn steering wheel

2) temperature is cool (60 degrees or lower)

3) only when I first get into car and start to drive



Can you help me solve the mystery? Thanks.

It could be a problem with the power steering pump. See if the serpentine belt looks like it needs replacement, and if the tensioner is OK.