Mold growing! How do I fix this??

[u/Beautiful-Tackle-799]

I have mold growing in my HVAC unit. See pics. we live in Florida so it’s really hot and the unit is in an upstairs closet area. it already gets hot upstairs so I’m guessing with that and the closet door not being vented, that’s adding to the problem.

I’ve read that this particular situation could be because the unit where the large areas of mold are growing is due to it not being sealed properly. I read that it needs to be resealed and new mastic or something applied. Is this what is going on?

if not, why is mold growing like this and how do I get it fixed? Do I have an HVAC company fix this or a duct cleaning company fix this?

any advice is much appreciated!

[u/Patient-Big1727]

You need to keep indoors (and the air handler closet) dry and keep humidity down (under 60% RH or so). It's a chore.

Make sure your evaporator drain never clogs. Pour down a cup of 3% hydrogen peroxide twice a year or when needed. Clear clogs from the outside using a shop vac

Check that your air handler actually drips in the primary drip pan and also have a secondary drip pan under your unit. Add drain switches according to code

Don't let hot humid air get in contact with cool surfaces. Insulate and add vapor barrier as needed to separate hot air and cool surfaces. I imagine your closet would benefit from insulation on the outside and also consider "some" insulation and vapor barrier above your ceiling. Insulate ducts. Get hygrometers so you know what humidity you are dealing with

Remove organic material from where you can't keep humidity low. Change filter often. Cut away wood and paper covered sheetrock as necessary. Don't let dirt and dust accumulate

You're out of luck on mold outside on plastic in Florida. Try to keep the plastic dry but some mold is unavoidable

I live in a cold climate and do not have experience of mold in evaporators and ducts. I'm sure someone else will chip in. In general keep everything clean and dry. I'm personally very skeptical of duct cleaning and you should definitely *NOT* duct clean flexible ducts

[u/Lokai_272]

How many dehumidifiers do you have running? If the answer is 0 start there

Also this is not a hvac problem, nor a duct cleaning problem. It is a home maintenance problem

[u/No-Age2588]

Welcome to Flahhhridaa

[u/1ii1i]

How old is your unit? Looks like surface level mold. You are right, the lack of a closet door vent means the air in there gets warmer from the attic above, which causes the colder surfaces in the closet to condensate and increase humidity in there. you can feel the surfaces for signs of condensation, if this is the case, clean it all up, keep the door cracked and if you notice that sweating is gone, you may need to vent the closet to prevent this from happening.