We recently have a musty smell in our house,especially in the master bedroom which is adjacent the heat pump. We can smell it through one vent in that room but not the other. I went under the house and determined there was no apparent moisture. Someone suggested an ultra violet light in the duct might help. Any suggestions? Hasanyone had experience w/ a UV light? Howmuch does it cost initially and does it need to be replaced periodically?

I would suggest contacting a furnace/duct cleaning company, and have them locate and remedy the source of the smell.