Probably because of the humid warm weather our rear Cruisair developed a musty mildew smell. While on vacation I opened up the wall and cleaned the unit. The condition improved, but did not go away. I called Cruisair and they told me to use hydrogen peroxide to eliminate the smell. Put the hydrogen peroxide in a spray bottle and apply directly onto the aluminum fins. As it drains it should clean the condensate pan as well. I am glad I called because I was planning on using Clorox which it turns out could damage the fins! Ken