Hyundai Repair: squealing belt, belt tension, alternator belt

Question
After replacing my a/c belt, it starting squealing when the a/c or heat is on, but isn't as bad once the car warms up. I just replaced the belt again yesterday and still the same issue.  What else could be the problem?

Answer
Hi, Joy.  I got the additional message that this is a 2005 Sonata with the 2.4L 4 cylinder engine.

Most likely, the alternator belt is loose.  Running the heater or air conditioning puts significant additional load on the alternator, which in turn will cause a loose belt to begin squealing.  Recheck the alternator belt tension, tighten as necessary, and follow up if you continue to have a problem.