Pontiac

I have a 1997 pontiac grand prix gt. it does not have dual zone climate control. when i turn he a/c on, the three vents from the middle to left side are warm but the 2 right vents from middle to right are ice cold. somebody know why? when i put it on defrost, the left side of the defrost vent is warm while the right side is cool. same thing when i direct the air to the floor. the left side air vent on the drivers side is warm but the right side is cool. when i turn the climate control all the way to red (hot), all vents are hot. when i turn it back to cool, the right sides are cold while the left is warm. my first thoughts were that this car has 2 blend door actuators but only cars with dual zone climate control has that. this car does not have it and i only see 1 blend door actuator on the driver side of the heat/ac box. what can the problem be?

Maybe the blend door is only opening part way? if the split for left and right is close to the actuator i could see a temperature difference left to right. if you are positive there is only one blend door i would remove and check for full range. i also disagree with the above answer, mechanics are not the only ones that can fix a car.