The vent tube has become disconnected under the dash. You'll need to remove the stereo and heater control panel to gain access. Reconnect the hose and put everything back together.
Remove the vents and screws under the ac cluster speedometer cluster.
mine did the same thing, I had to remove the blowning unit under the passengerside dash,, and replaced it from a junkyard,, 20 bucks,, its hard to get ini and out but with some patience you can do it
You have to take a flat head screw driver and pry out the clock in the middle of the two vents. Next, unclip the wired and unscrew the screw in the back then there are two screws above the shifter just unscrew them. then pull the whole cover off and undo the screws of the radio and pull it out.
it would depend on the year of the accord. Does the defrost work or the heat in the floor work if so the line for swapping control is either broke or has come off. you can check the lower side by looking in the drivers side under the dash.
Don't know what vehicle you have but, sounds like the duct work came apart for the middle vents.
Check for a vacuum leak either under the hood or under the dash Check the operation of the vacuum actuated motors under the dash Check the operation of the selector switch at the dash
This means that you have either an issue with a vacuum line or one of the a/c - heater doors behind the dash is not working correctly and you need to start off at the a/c - heater controller to check that all positions are working...........
The turn signal flasher switch is mounted on the steering column left side. The hazard light flasher switch is is the red triangle mounted on the dash dead center between the A/C vents.
Remove the vents and screws under the ac cluster speedometer cluster.
If you are refering to the vents near or on the door try toggling the switches near the steering wheel. One is marked L and the other R. You can move them up or down.
the middle vents only supply air from the ac unit using a separate in dash fan. the floor and defrost vents come only from the heater
May be nothing more than compressor belt is slipping or A/C compressor may be getting "tired" an may soon need replacement