Can smell mold but can't find it

I had this problem with a pop-up trailer and found the door was trapping water inside and it was causing the smell. I know pop-ups are way different, but I wouldn't rule anything out.

Thanks for the update. Others can learn from your experience.

Cap off those unused pipes.

Found it! We had an unused dishwasher in our rig and I took it out and replaced it with drawers. I left the pipe without blocking it thinking that the turn-off valve would keep the pipe from leaking. Not so. The pipe, which was snugged up against the inside of the kickplate leaked, ever so slowly, and the kickplate, made of plywood, soaked up the droplets by capillary action. There was no evidence of dampness when I looked under the drawers, but I missed the water soaked and delaminated kick plate. I ripped the kickplate out and used a heater to dry things up. Next will be to buy a plug for that pipe and install a new kickplate. Life is good.

We were in heavy chipmunk surrounds and once had a chipmunk die in one of our bay compartments -left the door open for him to walk right in :). A couple weeks later the strange moldy smell began. We emptied the bays and found it. Washed his resting place and no more smell. A mouse might smell the same!

I know this will sound silly, but it could be your screen door. For some reason, the dust on screen doors has an awful smell to me. Also, old wallpaper. Clean your screen door and window screens to see if it helps.

It took me a while to figure out a smell at home and it was the sliding screen door that needed cleaning.

MM.

In Florida, some pest control companies have trained K-9 dogs to detect and locate mold in a house.

Perhaps the same service is available where you are, and may be money well spent to find out, (usually within two feet) the exact location.

Go rent an ozone generator then close everything up and let it run for a day or so, until the smell is gone. This will kill any mold and the ozone can get in to cracks that you can't see. Naturally the smell will come back if the leak is still present so this is only helpful if you have found a leak and repaired it completely.

It took me at least a year to figure out where the moldy smell was coming from in our Class C. Then one day, I noticed water dripping on the outside corner. Turned out that the fill hose attached to the fresh water tank had a crack. The tank was under the dinette bench. Had to have it removed and fixed. All is good so far. I placed one of those "Cinnamon Brooms" in the corner behind the bench to get rid of the smell. Now it smells like cinnamon buns. YUM.

Underbelly.

Pogoil.

The other thing to think about is the air check valves under the sinks. Both bath and kitchen will have them. Fairly cheap and easy to replace. The smell might be coming up from the gray tank and threw a bad seal in the air check valve.