Bad Odor / Smell in A/C system
I bought a 2000 Explorer with the problem. Briefly rehashing what I learned on line that WORKED:
a. Remove the blower fan. It is in the engine compartment, not hard to remove if you are deliberate. You must unbolt the coolant overflow and windshield washer containers, but leave them in place. They only have to move a little to allow the fan to be removed. There is an electrical plug and a drain hose to detach, pretty easy.
b. Once the fan is out, you can see the condenser in it's housing to the right. Get a narrow flex vacuum hose and get all the dead leaves and stuff out that you can reach; hit it with an air hose if you can to dislodge more; then use a nozzle on a garden hose (It should all leak out the bottom). You will have difficulty reaching the lower right corner where a lot gets wedged. A small hand can carefully get more out - no pointy objects!
c. You can go under the car where the drain is (in my case it is not a hose but a molded opening about the size of a quarter; 1/2 covered in plastic with the opposite half covered about 1/2 inch higher (like a maze). No wonder mice get in these sometimes... and blow it up backwards to try and dislodge more, then repeat the process. I hit it all with lysol spray while it was open (but this will not be enough...)
d. Reassemble...
e. Go to your local Toyota dealer parts department and ask for the "spray kit that gets rid of condenser odor". He will eventually produce a two can set with a hose, charge you about $20.
f. Drill a small hole in the top of the condenser case close to the corner you couldn't quite reach, apply the spray the way it says to. It will fill it with foam, kill bacteria and drain out the bottom. There is enough in the can to do this three times, and you need to. Use the deodorizer can after this is done, per instructions. Plug the hole with a screw and washer in case you need to come back again...
g. Two months later all is still great. Remember it either happened from leaves and such dropping in the intake from the top or from rodents entering from the bottom and take appropriate preventative measures.
Good luck