musty smell from air conditioner

2oldman...

Made me smile :)

I use steaming hot (vapors) of strong concentrated sodium hypochlorite and water and let the inlet suck it through the system. My fetish started shortly after the first mass attack of Legionaire's Disease hit the presses.

Tropics seem to be MIT for fungus and mold. And diluted bleach seems to be the magic bullet. At least for me.

You can get a cleaner designed for that purpose from a car dealership. The stuff Ford sells works great from my experiience. It gets sprayed into the air intake and then is left to sit for a while.

Clean the evaporator coil - lots of "how to" post.

Yup, you need to get up on the roof and access and clean the EVAPORATOR. Clean the condenser while you are there.

The box stores all carry evaporator cleaner. And, that is what you want to use, as it is OK to breath, and whatever is on the evaporator WILL get into your coach air system.

This needs to be done annually, more often in very humid climates. The air filters on RV air conditioners are poor at best. So, combine condensation (water) dirt, heat and what you are smelling is all kinds of little "gremlins" growing. Get rid of them.

All of the above, plus I do one more thing which is go to the dollar store and buy a can of spray disinfectant. I run the unit and spray the can into the air intake. Then when I can no longer stand the smell I spray what's left into the outlet vents after I shut off the AC.

I plan on being gone for a good long time (4 plus hours) after spraying. I do the same thing with the furnace when it get's later in the season.

On edit:

One thing that didn't get mention is to keep an eye on the squirrel cage fan. That thing can get loaded up over the years and give off the dirty sock smell.