2001 Audi A4 heater problem

[KCaudiA4]

soooo... for some odd reason the heater stopped blowing warm air into the car. im pretty sure it still works bc when i first turn it on it will be warm for about 30 seconds. but it doesnt keep blowing warm air, it always gets cold. just wondering if anyone else has gone threw this problem? any possible solutions?

[Dubtuner]

ehh is the car adequately warming up? As in getting to temp? or it could be a problem with a blend door or maybe a clogged up heater core? Just some thoughts

[KCaudiA4]

it seems to be warming up like normal. i havent seen any changes in the temp guages or anything so no worries there. i have heard the blend door thing, i think this might be it. how do i swap that out?