LESLIE: Jim in North Carolina has an air conditioning question. What can we do for you today?
Eliminate Air Conditioning Odors
JIM: Well, hi folks. Love your show.
TOM: Thank you.
JIM: I have a problem with a musty odor that comes out of my air returns – well, several of my air returns – when the AC first kicks on. And I noticed this last summer and put a vapor barrier down in my crawl space and put a dehumidifier down there and it may have slightly improved the problem but I still get that musty smell when it kicks on.
TOM: First of all, you say it’s coming out of your returns. Do you mean your supplies?
JIM: Well …
TOM: Because you shouldn’t have anything coming out of the return.
LESLIE: Things should be going in.
JIM: Well, OK, I’m sorry. Yes, the vent – the floor vents.
JIM: Yes, yes, yes.
TOM: When the system first kicks on, you’re going to have a lot of moisture and humidity and perhaps even some condensation inside the duct system, so that doesn’t surprise me. Does it dissipate within the first 15 minutes?
JIM: I would say within the first minute or so.
TOM: Yeah, that’s pretty normal. I think you’ve got a lot of moisture and humidity inside the ducts and you’re probably just taking that into the air and sort of throwing it back into the house. I don’t think that’s anything to be concerned about. If you want some general suggestions on how to reduce the amount of humidity in the house, putting the vapor barrier down was a good first step but there are other things that you can do outside the house.
Take a look at the grading; the angle of the soil around the foundation. Because if you collect a lot of water around a concrete foundation, it’s going to soak through and evaporate into the interior air space one way or the other. So improve the grading. Take a look at the gutter system. Make sure the downspouts are extended out away from the foundation.
LESLIE: Make sure the gutters are clean.
TOM: Yeah, good point. And take a look at the ventilation inside the house. Make sure that your attic is well-ventilated because you get a certain amount of vapor pressure inside the house where the humidity sort of pushes up through. It’ll end up in the attic and if it can’t easily vent out, that will also cause an additional humid sort of musty smell inside the main living space.
JIM: OK, great. Sound like good suggestions. Thank you very much.
TOM: You’re very welcome. Thanks so much for calling us at 888-MONEY-PIT.