Osb board around AC unit looks wet, smells of mildew

[Rosemary]

I pulled up carpet and vinyl in hallway and noticed that osb board is darker (wet I guess) Smells like mildew. This area is around the AC unit. I assume that the AC pan overflowed at one time before I moved in. There is always about 1/2 inch or less of water in the drainage pan of AC. The Ac was filthy when I bought the house and coils covered with sooty black material which I cleaned. The drain is draining outdoors. Is it possible for me to clear drain out so pan will be dry? Also, will I have to replace the OSB board? I sprayed a little clorox on it. I assume that the board beneath the ac in the closet is also wet. Is it a big chore to remove all of the unit to get to the board for repacement?

[Yanita]

Hi,

I am going to move this to the repair forum.

Yanita

[JD]

Hi Rosemary,

You can clear the drain line and pan by attaching a wet-vac to the end of the drain pipe. Running a strong bleach solution through the pipe can help clear it of algae build up, which may be clogging the pipe.

The OSB may be OK, depending on how much water it saw. If it warps or shows any sign of mold, I would replace it.

JD