Toyota Repair: 1999 corolla heater smell, mold remover, air ducting

Question
QUESTION: i HAVE A SMELL FROM THE HEATER VENTS THAT i GUESS YOU WOULD CALL MUSTY. after DRIVING THE CAR WITH THE HEAT ON WHEN YOU COME IN THE HOUSE YOU HAVE THIS ORDER ON YOUR CLOTHES AND EVERYONE IN THE HOUSE SAYS YOU STINK. I saw on a few sites that it could be a heater core. HELP ME WITH THIS PROBLEM I have done everything I can think of.

ANSWER: The heating/ac system can be deodorized using a kit available at most autoparts stores, it involves drilling a small hole into the air ducting and releasing a foam disinfectant/mold remover into the air ducting which will clean the a/c evaporator core, this is normally where the smell is coming from, if you don't feel confident in drilling a hole into the ducting then have a repair shop or the dealer do this as drilling in the wrong place can damage the a/c evaporator or other parts. At the same time this is done the a/c evaporator drain hose should be checked that it's not restricted and can drain any water to the outside under the car.

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QUESTION: after drilling a hole and spraying this foam disinfectant into the system, how does it get removed or does it just evaporate in the system and the air ducks
have you run accross this problem before? Like I had told you it is musty smell as in stale air. I have done many things including replacement of the carpet,head linner new mats and complete scrubing and having this car recondioned
I just do not want to chase this smell with more money. At this point I emailed you. This car was bought for my son and other than this problem it is a real good car and perfect for a kid that just got his licence. Please let me know if you really think that what you have told me to do will fix the problem
         Thanks
         Ronn

Answer
It will fix the problem unless a small animal, rodent, has gotten into the ducting and died in there, that's a possibility and wee see this here in california frequently and there is a possibility that it may be the problem if you live in a warm climate with colder winters. Mosty of the time the smell of a dead rat is very severe and distinctive so from what you have said so far that this is a musty smell this may be only due to moisture residue in the evaporater ducting which can create mold and mildew, in some cases this happens in humid climates because the climate control is always set to " recirculate" rather than on the "fresh" setting, it can also be caused by water not draining to the outside through the drain hose on the bottom of the air duct housing. The chemical used in the process will evaporate and exit through the air vents.