Heater problems

In my 99 GA when the heater or A/C is on there is a high pitched noise, but when i turn it off the noise continues for about 2-3 seconds...what could it be?

sounds like your blower motor is going out.
Probly due to water in the blower housing.

You'll need to inspect the motor and the hvac drain for a clog, it's on the pass side.
see this link...
Blower Motor & Resistor Removal - 99+ Grand Am (http://www.automotiveforums.com/vbulletin/showthread.php?t=665246)