Odor from the vents

[Teodoro_Jimenez_at_IRV006@xxxxxxxxxxxxxxxxxxxxxxxxxxxxx]

     Does anybody know how to get rid of stale odors coming from the vents 
     of a 97 328i.  I tried to spray Lysol in the vents and the odor is 
     still there.  The dealer will clean the vents and replace the 
     evaporator for $250.00 (kinda expensive).  All other BMW owners have 
     said it will eventually go away (it's been stinkin for over a month)
     
     By the way, the odor is only noticeable when the fan is turned on, not 
     when the ac is on.
     
     Any help would be appreciated
     
     Teo

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