02 Santa Fe LX AWD Radio cuts off possibly alternator?

My wife told me that today when she was driving her 2002 Hyundai Santa Fe
the radio would cut off when stopped with the lights on, radio on, and the
AC on, when she took her seat belt off. She said when she turned her lights
off the radio came back on. I have noticed that when a start from a stop
the AC fan kicks up a notch in speed without an increase on the instrument
panel. I think I remember hearing about a problem with the Alternators?
Any advice? The car has 40k or so on the odometer so I am pretty sure that
anything wrong will fall under warranty but I figured I would ask so if the
service technician asks what's wrong I can say with confidence what it is.

 

Your service technician is going to be primarily interested in the symptoms
and won't expect you to be able to tell him the cause of the problems.

It sounds to me like you have two separate issues. First, it sounds like
you have a problem with the radio itself. Unfortunately, the radio
warranty is 3yrs/36k miles, so it won't be covered. The fan speed
changing may be normal, especially if several high load items are turned
on. The alternator's ability to deliver voltage and current is limited at
idle, so if the lights brighten a little and the fan speed kicks up a
little when you step on the gas, it's possible this is normal. Similarly,
it's also possible that you actually have an alternator or battery problem.