Interior Venting Problem

[sdk444]

I have an '05 accord coupe ex-l. my heating and cooling system works great. one issue. the right side of the front windshield doesn't get air when i put the vents on the defrost position. this includes the right half of the front windshield and the passenger window. the left side works great and everything else works great. Right side torso and leg air comes through just fine. only the defrost vents dont get air.

I have no idea what to look for. Could the vent have come loose with a bump? I wouldn't even be sure in saying they're different vents.

thanks!

[sdk444]

Ok time for update. The problem has not been resolved. The entire right side is blowing cold air when the heat is on. It also feels as though when the fan is on full the left side (the side that is hot) is not coming out full force. The right side thats not working includes the right half of the defrost vent, torso, leg, and passenger window vents. I was hoping to maybe get an idea from someone before having to take it to a mechanic

oh btw, i've discovered there's something called a heater control valve. small box like piece with two connections for hoses. If both sides didnt work I'd feel comfortable in saying this was the problem. unless there's a valve for each side of the car? lol im lost