We just purchased a home in Florida. The house is two stories, built in 1933, wood frame colonial style. The house is approximately 2200 square feet with 1226 downstairs and 950 upstairs. There is an attic and crawl space.
Downstairs is cooled by a 3 ton Trane heat pump package unit. The upstairs unit is a straight A/C 2 ton Tempstar. The air handler for the 2 ton unit is located in the attic.
The upstairs of the house feels damp and also has a musty smell. Actually the smell is throughout the house, but is most noticeable upstairs. I have observed a small amount of mold/mildew growing on the inside of two cedar closet doors that are located in the hall upstairs. The closets are very small and get no air circulation when the doors are closed. They have a very strong musty smell to them. The cedar ceilings in the closets also feel damp at times if the doors are left closed. If you leave the closets closed for a day and then open them you can "feel" the humid air inside. There are no a/c vents in the cedar closets.
After reading a few posts on the site I went to Radio Shack and purchased a hygrometer. I have recorded humidity readings in the 67% range (during the day) in the upstairs bedrooms.
Our home inspection indicated the upstairs unit had a temperature differential of only 10 degrees. My initial reaction is that the unit upstairs is undersized and not pulling enough moisture out of the air. I am assuming that the damp conditions upstairs are causing the musty smell in the house.
I don't know where to start. OPINIONS PLEASE!!! on how to deal with the humidity and the smell.