Heater Problems

The heater on my K11 isn't working properly. The fan goes through all its speeds and you can hear that it is spinning as loud as ever but the air is pretty much just trickling through, even on the highest setting. The highest setting feels like the lowest setting used to.

Also the air is never more than luke-warm even when the car has been driving a long time.

Does anyone have any ideas? Thanks!
 
Exactly what mine did
Pull the glove box out (two clips at bottom)
Pollen filter is behind plastic panel there's clips on the bottom and you have to cut the plastic behind the glove box to pull the filter out
 
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