Condensation???

[Hikingsolo]

My trailer was left for the winter in Show Low, Arizona where temperatures can get close to zero. I’ve winterized the last eight years by carefully blowing out all lines, putting antifreeze in the traps and making sure all filters are removed.

This year I opened up to find a fine deposit along the interior roof seam on the northwestern facing side of the trailer. It wipes off easily with a damp paper towel. I’ve never had anything like this happen in the past.

Picture below.

Thoughts?

- Allen

[Shinytoaster]

I was going to say 'salt' or some other cleaning solution that has dried out and crystalized... but I don't think so. AZ is very dry so unless there was a lot of water around (sounds like there wasn't), I don't know - sorry.

Tho' possibly a mold that has sporulated from moisture there before you parked up.

[cwf]

That looks like a floor corner… anyway, is this a vented AC ceiling/ roof?

[Hikingsolo]

The picture is of the ceiling near the refrigerator.

This was an unusually dry winter, although fairly cold. First time I’ve seen anything like it.

[Bubba L]

Looks kinda like efflorescence. If at one time you had humidity or moisture inside the wall at that location, moisture migrating to the dry side brings soluble salts and minerals that dry on the surface. We had seen a lot of that on brick buildings and houses where moisture got in the cavity and dried to the exterior bringing the white powdery minerals with it.