ok ive looked around the forum and cant find anything specific to my problem.
when i first start the car the air vents are stuck on dimister but after say 20-30mins the will slowly change to whatever i have them set at, but then if i change what i have them set at too much, it gets stuck on dimister again for another 20-30mins?

any reason for this? and if anyone has any idea how can i fix it?

thanks