My 2 side air vents blow hot air when a/c is on while center vents blow cold.

In the center of the middle A/C vents on the dashboard, you will see both a blue and red button. If the blue light is on, then you will get cold air through the center vents regardless of the preset temperature. If the red button is depressed, you will get warm air through the vents, if both lights are off, the the air coming from all of the dashboard vents should be the same temp.