I am having trouble getting rid of a smell in my AC (installed 2016), 2 visits by an HVAC professional have resulted in no luck.
Problem:
There is a musty smell, from all vents, as the AC is turning on and just after it turns off. While the air is at its peak cold, there is no smell.
- We have a variable speed fan, which we were told could/should run all the time (on low) to keep air circulating. We like to leave this on in the summer (off in the winter).
- If we turn the fan off, smell isn't noticeable, as smell is worst when fan runs after AC.
- First visit by HVAC professional, we were told everything was fine, probably dirty air ducts.
After this first visit, I did some investigating, I carefully removed the outer panel over the AC evaporator coils. When I did this I could instantly smell the smell coming off of the coils as soon as the compressor came on, again no smell while its running, but smell comes back as the compressor turns off and remains for a few minutes.
HVAC guy came back, decided evaporator coils needed to be cleaned, sprayed them, and left. Smell got better, especially while you could smell the cleaner, but came back after a few days.
After this, I purchased a can of cleaner and repeated the process, and again the smell came back, but doesn't seem to be as bad.
- Do I need to just keep re-applying the cleaner until its gone? The coils look clean (the HVAC guy removed the inner panel to see the inside, and its pretty clean.
- In the last 4 years, we have run the fan on low 24/7 during the summer and haven't had this issue.
- I poured water/clorox down the pan/drain, but it looked pretty clean.
I don't think its dirty ducts, but am willing to pay to get them cleaned, but want some more advice before spending money on something that has questionable effect.
Thanks
Best Answer
Musty smells in the evaporator coils are common. You really need a flaming cleaner and the coils need to be cleaned 2-3 times to get everything out. I use a product called Nu-brite from My-Calgon it is a non acidic foaming coil cleaner, make sure your drain is working prior to use of it will make a mess. The foam pushes the dirt out. What you are smelling is dust and grime when the system runs it collects moisture now that dust and grime are the “smelly socks” breeding ground you don’t smell it mid cycle because it is frozen at the start and end when the coils ate thawing you get the full odor.
1 cleaning usually helps 2 may do it but 3 has fixed even the worst (smokers) coils I have encountered with a clear water rinse after each cleaning. Cool cleaning is suggested at least 1 time per year and with heavy use 2x.
Always have a filter in your system or this can start in just a few hours with dusty conditions.
Whatever you use don’t use an acid based cleaner acids damage the aluminum fins and shorten the coil life.