airman1, i have been reading the posts on musty smells in a/c systems as i have the similar problem with my in the attic unit. i have a hydro air system, triple by-pass 1 1/2 years old in my new house. this is the first time i have ever had this problem and the first time i have a split system with a unit in the attic. i am in massachusetts. i have checked out the attic...no problems,
i have checked out the unit along with my son-in-law and its sealed good.
my son-in-law has been in the hvac line for at least 20 years and hasn't heard about the dss problem and either have i. i have had 4 new houses so far in my time, i'm 63 yrs old. my son-in-law cleaned the coils and the system ran with no smell. the next day the smell was back. when we open the attic pull-down stair and start up the ladder you can smell the musty oder slightly.
you talked about coating the coils...what is the coating? will any coating work?? i'm in the process of investigating so i only have to do somthing once to fix this. sounds like coating the coils works best. i did think about installing an exhaust fan....my house is new with the typical ridge and soffit vents with proper venting but coating the coils sounds like the way to go. we don't hear of this problem in my area but i'm sure its out there. you don't happen to know of any coating places around massachusetts do you??????
i'm in the design field drawing plans for commercial & residential buildings.