I had same problem.Then...............I found where the water was really coming in from and it was a disaster.Not saying thats your problem but I found one small damp area in a compartment and could not get rid of mildew smell.Well come to find out after a heavy rain ,well during a heavy rain the water was coming in from bedroom slide area and the entire bottom of slide was soaked black mold.I lifted the carpet on slide and literally pulled with my hand ithe black plywood that disolved in my hand as I grabbed it.So that was my source of the smell.