Had the air ducts cleaned today. Guy asked me to come to the attic so he could show me what's going on. The box feeding the ducts delivering air from the A/C to the home had mold all over the insulation. No mold in the ducts or on the vents in the home though. They cleaned it and used whatever chemical they have to prevent mold growth but said it's likely to return.
He recommended a UV light to prevent future mold growth. Some quick searches on my part show they work but some hvac guys also recommend filters as a much cheaper alternative solution.
He also said we shouldn't have the filter in our unit in the attic. Instead use filters on the return air vents inside the house.
Thoughts???

don't know about the mold stuff but our A/C guy says if your system has a place for a master filter in the attic, you use that and don't put any in the returns...which would cause the system to work too hard to pull air.

I'm sure every A/C guy has their preference, but if the system has a place for a master filter, I would think the manufacturer meant for it to be used. A return is a return is a return.

My thought as well. Use it as it was meant to be used. Gracias.

Mold thoughts anyone???

Uhm....the system is dripping with condensation and filters don't remove every spec of dust coming through. Dust is organic. Mold likes wet, organic things. Finding mold in an ac system and upselling a uv filter is just good marketing.

I have a uv light and electronic filter in my system but still use cheap fiberglass in my return vents to catch big stuff. It extends the life of the expensive stuff in the air handler.

For you I'd much prefer cheap fiberglass in the returns and a good box filter in the air handler if it has provisions for it. There is zero reason not to sue a fiberglass filter in the returns. Always. They don't restrict flow appreciably and if you have pets they catch big stuff.

But mold in the air handler...yeah...well...sky is blue, water is wet....so what.

Not all mold is equal. There is the mold that is really mildew, and that can be cleaned up but it is part of home ownership. Then there is mold that presents health challenges -- that's a different story. Assuming you are talking about the former, take precautions, clean things routinely, and drive on.