My air conditioning is stuck on the vents in my 2005 Nissan Sentra. I turn the knob and it won't change from defrost. Is there an easy fix or will I have to take it to a repair shop?

MODE ACTUATOR IS INOPERATIVE. LOCATED BEHIND RADIO ON THE DUCTWORK

Check for a vacuum leak in the control panel

HERE'S A LINK TO YOUR SET UP,SOMETHING COULD BE BROKE,NOT LETTING YOU TO ADJUST WITH THE SWITCH,THERE ARE CABLES ATTACHED TO THE LEVERS THAT MAKE THEM TURN WHEN YOU TURN KNOB,MAY BE LOOSE,BENT OR BROKE,YOU WILL HAVE TO REMOVE THINGS AND SEE.

check for a broken /loose vacuum line on the engine . Trace it back to the fire wall and it will most likely be the culprit/

The flow switch it change's howthe air flows get a motor manual at auto parts stir about 25 bucs it will tell u what up

Check the condition of the heater matrix valve under the dash board. Disconnect any motors or cable connections to it and try operating it by hand. If it is stuck, then replace it.

If not stuck, then check motor operation (if climate control model) or cable routing (if manual only).

This is usually caused by the selector switch being bad on the car. You will need to change the switch for it to work again.

vent door is stuck open

a/c is active when in defrost mode to remove moisture from air. what controls the movement from vent to heat/ or defrost. a lever or switch.