Bleach Odor Inside Miata

I have a 2000 Miata that has a “bleachy” smell inside. Once I drive it and put on the a/c vents, it clears up. The Mazda dealer has checked it out & found nothing. They said the radiator was cracked & leaking, so they replaced it, but that was not the source of the odor. They also checked the gasoline tank, but no problem there. We have cleaned the car from top to bottom, the odor remains very strong.