Welcome to the forum!

I'm no expert in this area, but I've seen some threads with the same complaint.

Try a search on A/C or air conditioning, or vents, etc. Perhaps the solutions outlined on those posts will also rectify your problem.

Good Luck!

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2009 ML350 (106K) - Family vehicle
2001 CLK430 Cabriolet (80K) - Wife's car
2005 BMW 645CI (138K) - My daily driver
2016 Mustang (32K) - Daughter's car