bad mold smell from 1997 Honda Accord AC

I have over 200K on my 97 Accord. I recently had one of the valves replaced on the AC unit where they removed the evaporator. They found a ton of mold in the evaporator case and cleaned it out with bleach. I always did often have a mold smell come out of the AC when it started up for a few minutes. Now after the recent AC work, the mold smell is worse yet still only is apparent for the first 10-20 minutes of driving. My mechanic said nothing much can be done. He sprayed some of that mold fighting aerosol into the evaoporator without much luck. I have been turning off the AC and putting it on fresh air a few minutes before my destination, although again the improvement is only slight. Is there any other thing I can try to help fix this problem.