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airheatman, HVAC Technician
Category: HVAC
Satisfied Customers: 8370
Experience:  Furnace, A/C and heat pump specialist.
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We bought a house in 2014 and immediately noticed a “moldy”

Customer Question

We bought a house in 2014 and immediately noticed a “moldy” smell from the HVAC system in our crawl space. We discovered a clogged condensate drain (and a drain line that emptied directly into the crawl space!), mold in condensate pan, etc. We’ve had the pan & line, blower assembly, and coils cleaned (and also sprayed with bio fresh cd). We also had the ducts cleaned, and I’ve taped the seams on the ducts. Unfortunately, we still have the sour/earthy smell coming from our registers when the AC kicks on.
Our HVAC guy is unconvinced that there still should be a problem (even though he seems unwilling to do a smell test). I worry that there’s still mold on the underside of the coils, which he didn’t access, although his experience is that the external side is mold free, the underside should also be mold free. I talked to a couple other HVAC guys, and neither of them had any solutions.
Is there something else I’m missing? Should I consider getting new evaporator coils?
Submitted: 2 years ago.
Category: HVAC
Expert:  airheatman replied 2 years ago.

Did they recover refrigerant and remove the coils to clean them?

Customer: replied 2 years ago.
no, he did not remove the coils - he just cleaned the "supply air" side of the coils, which was accessible (the return air side was not, which is part of my concern)
Expert:  airheatman replied 2 years ago.

Coils should be removed and cleaned as if there was mold on contaminants, it has most likely been drawn between fins of coil also.

It is also a good idea since unit sounds like it is located in a somewhat damp area, to have them install a uv light in the duct to prevent regrowth.

Customer: replied 2 years ago.
thanks - before we discovered the mold, our first HVAC tech installed uv-air cleaner, but it's on the return-air end of the system. Should it have been installed on the supply-air end?Also, as I mentioned, the second HVAC tech has been resistant to remove the coils, so I'd appreciate any suggestions on how (in addition to hiring yet another tech) to convince the tech to do the job you recommend?
Expert:  airheatman replied 2 years ago.

The uv light should be on return side or just above coil.I would suggest you have him remove coils and clean them.Also make sure the ducts are actually clean.Ask them to show you inside the ducts .Most people who clean ducts have cameras that allow you to see the results.If mold is still growing, make sure cfms on air handler are correct.