Maybe try a can of this stuff. Any good ASE repair shop in your area will have it.
BG Frigi-Clean®
Odors, bacteria, mold, spores, fungi, road grime, nicotine oils and debris accumulate in your car’s air conditioning evaporator. BG Frigi-Clean® restores heating/cooling efficiency and freshens interior air. It is a unique cleaning solution designed to quickly and effectively remove foul odors, bacteria, mold, spores, fungi, road grime, nicotine oils and debris that accumulate in your car’s air conditioning evaporator. BG Frigi-Clean® is injected directly into the evaporator case. It foams up to completely fill the evaporator core where it also blasts away bug parts, pet hair, nicotine residue and other garbage. BG Frigi-Clean® is biodegradable, non-toxic, non-corrosive.
Part No. 709 Net Wt. 7 oz. (198.4 g)
Volume 6.65 fl. oz. (197 mL)
or this one...
BG Frigi-Fresh®
BG Frigi-Fresh® is formulated to quickly and effectively eliminate foul, musty odors from automobile air conditioning systems. It kills mold, mildew and other odor-producing organisms that grow in the evaporator core and housing. Powerful deodorizers in BG Frigi-Fresh® keep the automobile interior smelling fresh and clean. EPA Reg. No. 44446-20-67145.
Part No. 7083
Part No. 708 Net Wt. 1 oz. (28.3 g)
Volume 1.12 fl. oz. (33.1 mL)
Net Wt. 5.5 oz. (156 g)
Volume 6.17 fl. oz. (182.6 mL)
http://www.bgprod.com/products/climatecontrol.html