A/C Smell

[TexasBob]

New unit, installed last summer. When we go from heat to cool, smells like a wet gym sock for 10-25 seconds. Have heard from others that this happens, seems to be an issue with newer units. Old one didn't do it. Can it be prevented? Reading it is slight mold buildup- will a UV light help?

[Txhuntr2]

Good question. Mine does it every time when switching from heat to cool. But doesn’t do it again until I have to turn heat back on then switch again. Unit is 5 or 6 years old.

[bowhntrmatt]

Its called dirty sock syndrome and can be an absolute PITA to make go away.

I have a fairly new system, ultra high efficiency, UV light, ionizer, PCO purifier, best filtration available, and still have it every time I switch from heat to cool.

I’m also in residential HVAC by trade, and have had to deal with it in numerous customers’ homes. Sometimes we can get it to go away, sometimes we can’t. Ac manufacturers have even put out service bulletins about it.

[Dakota7493]

Every spring when we turn the AC back on after the winter we have that smell for a few days and then it's gone.

[elliscountyhog]

There is a solvent that you can get and wash the indoor coil with that helps.

[TexasBob]

There is a solvent that you can get and wash the indoor coil with that helps.

Unit is 4 months old but willing to try it. Thanks for all the input. Reading good things about UV lights above and below the coils.


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[double bogey]

It is more prevalent with heat pumps than gas. The gas furnace discharges into the coil, and the increased heat kills the mold. A heat pump, the coil is the first thing the air hits past the filter.

Good filtration, and uv lights are what have worked for me when I have ran across this.

[Iehooligan11b]

Just had the same thing happen. Ran the AC the other day for first time in awhile and walked into the house and noticed a nasty smell coming from vents. Had no idea what it was.

[JANKEII]

Going through the same thing

[Fightinaggies]

Mold or mildew on the evaporator coil

[fishman]

UV light won't help.

[Bayouboy]

The one in my recently built home does the same thing. Only lasts a few minutes. Nice to know it is not out of the ordinary. No worse than the smell after a night of red beans and corn bread.

[be12hunt]

I’ve been dealing with it as well with our new unit. We have a UV light and does nothing for it. I also looked at the coil and it looks spotless.

I wanted to spray it down with some antibacterial/disinfectant but don’t want to damage the coils.

[TexasBob]

Agree with the above. Ours is spotless. Hell its 4 months old. Insane the 15 year old one didn’t have the issue


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[be12hunt]

Agree with the above. Ours is spotless. Hell its 4 months old. Insane the 15 year old one didn’t have the issue


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Yeah it’s frustrating. I’ve got a message in with a buddy that owns an HVAC business to see if there is anything he recommends.