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Mold contamination in the duct work

After we bought our house, we found our inspector had missed a 6" x 12" hole in the return duct line in the crawl space. There has always been "musty" odor coming from the registers and making everything in the house smell like the crawl space. We hired an hvac pro to seal the hole, we replaced the supply and return duct lines, as they had moldy insulation in them, and we had the outside heating and cooling unit cleaned and insulation replaced. We still have a musty smell coming from all the registers, but not as bad in the winter. We are not sure what to do next. All the ducts are free of insulation on the inside, so there can't be any constant contamination. Could small leaks in the branches be pulling crawl-space air into the ducts, or could there still be contamination in the unit. It's worse with the air-conditioning. We have very good allergan electro-static furnace filters. What should we do next? Could there still be actually live or dead mold colonies in the branches. Help, it's hurting my sinuses!:eek:

Re: Mold contamination in the duct work

The condensate pan under the a/c coils in the furnace could be clogged and keeping water from draining off properly. Mold could be growing there.
Did they clean the a/c coils in the air handler inside? They could be dirty.

Re: Mold contamination in the duct work

Thanks for the responses.

Well, the filters in our system are located on the return leg grills. We've changed these frequently (approx. every 2-3months). The condensate pan below the coil has had some what I would describe as gunk, which to me looks like dust/dirt mixed with the condensate water. This, however, has not caused blockage and we have had continuous drainage from the pan.

My husband has suggested that the coils need to be cleaned really well. We had a family member who owns a heating and cooling business do this once (bad idea) and my husband doesn't think it was done well enough.

This air handling unit is a complete outside unit. I don't know why they had to come up with that idea. It seems that this leaves the unit vulnerable to the weather.

Keep the advice coming! We appreciate it.

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