How to permanently stop AC moisture causing closet mold?« Back to Previous Page

The dampness and recurring mould are almost certainly from condensation due to a temperature differential between your cold AC supply and the warm, humid air in the closet. Bleach only removes surface discolouration but does not address the moisture source or the mould's root structure within the porous wall material.

First, identify the AC's condensate drain line. In many split units, a blocked or improperly sloped drain line can cause water to back up and leak, saturating the wall. Ensure the drain pan is clear and the line flows freely. For a more permanent fix, the AC unit may need to be serviced to correct the temperature differential; this often involves adjusting the refrigerant charge or fan speed so the evaporator coil isn't excessively cold, which causes excessive condensation.

Given the mould's recurrence, it has likely penetrated the gypsum board. Scrubbing the surface is insufficient. For a small area, a solution of white vinegar or a dedicated mould cleaner can be more effective than bleach at penetrating porous surfaces. However, if the mould returns, the affected drywall section likely requires cutting out and replacement after the moisture issue is resolved.

In a Marina apartment with high ambient humidity, an interior closet with limited air circulation is a prime location for condensation. Leaving the closet door open as much as possible allows conditioned air to circulate and equalise the temperature, preventing the cold wall from attracting moisture. For a more technical solution, a small duct can be installed to divert a small amount of cooled air directly into the closet space.

If the problem persists after these steps, a professional inspection is recommended. They can use thermal imaging to pinpoint the exact condensation points and moisture meters to assess wall saturation. Verifiable remediation, backed by before-and-after lab testing to confirm spore count reduction, is the definitive solution for persistent problems.