So I finised up detailing a 128i today from Florida- and it came out very well overall. One thing I was not at all pleased by was the gunk on the A/C vents. This picture is all I have because I've already delivered the car. However- I offered to fix the vents if I can figure out a solution. When I searched- I found discussions of A/C smell. To be clear- this A/C does not smell!
My problem is this brownish/whitish- slightly tacky buildup which I do not believe is discoloration. I'm sorry for the poor picture- the center vents were much worse than this one (much browner).
I tried a toothbrush with APC+ (4:1), OPC full strength, Invisible Glass, Tar-X, agitation, etc. I really removed very little of the substance with all of that work.
So tell me- what is it and how do I fix it? Would a vapor steam cleaner do it? Some product I don't know about?
PS: This car has not been smoked in.

My problem is this brownish/whitish- slightly tacky buildup which I do not believe is discoloration. I'm sorry for the poor picture- the center vents were much worse than this one (much browner).
I tried a toothbrush with APC+ (4:1), OPC full strength, Invisible Glass, Tar-X, agitation, etc. I really removed very little of the substance with all of that work.
So tell me- what is it and how do I fix it? Would a vapor steam cleaner do it? Some product I don't know about?
PS: This car has not been smoked in.
