[tommylmeeks@aol.com]

I had my down stairs heat pump, handler, and duct work replace three years ago. I Think my upstairs unit is about 15 years old. When the upstairs units kicks on There's a musky?, slight burning?, Dusty? odor that come out of the vent in the master bedroom. This is the vent that is on the very end of the duct work. I have taking the vent hoses off and they seem to be clean. I have both units serviced two time a year. Any idea what the odor is and why it only come through this one vent and not the other ones even though they are only 10 feet or so apart?