I recently experienced clicking from the dash of my 2008 Tucson but my problem was not being able to change the air flow from defrost to vent to floor. My mode actuator motor has gone bad. Tucsons have small motor assemblies with plastic gears that operate levers and doors. There are three of these motors 1) mode actuator which changes the air flow position 2) fresh air or recirculation and 3) blend door which adjust how much air passes through the heater core to mix with the AC to adjust the temperature. Sounds like your blend door motor is bad, it is on the passenger side. You can locate it by removing the glove box. The online part diagrams can lead to selecting the wrong parts, it helps to remove your bad part to ensure you can order the correct replacement. Good luck.