Mold or just discoloration?

Hi there -

An AC leak went unnoticed for a couple of weeks and went all the way through the attic flooring, insulation and sheet rock to start leaking through the ceiling. The leak was fixed, the water dried out and a fan was placed in the area to increase the ventilation. It has had 2 weeks to dry out at this point.

I have heard varying things about attic leaks - on the one hand mold is a huge issue, but I’m also told that most insulation is mold resistant and not to worry. Although I believe mold can cause a lot of damage health-wise, I’m hesitant to call a “mold expert” because i don’t want a $5k+ bill for mold removal when that could very well be overkill. I think remediation people start to get greedy when they see a homeowner that wants to be thorough.

The primary area is under the AC unit which I can’t really see, but there is discoloration on the plywood. Does this look like mold or simply discoloration/water stains?

This happens all the time with no mold issues hardly ever (if corrected in a reasonable time).
Mold requires temperature (attic is too hot most of the time which accelerates drying out the leak ), Something to eat (Fiberglass is not edible), and continued supply of high humidity*. Also the attic is outside the house. Air gets pulled into the attic from the living space of the house due to stack effect (Hot rising air that happens year round). Mold is not going to be pulled into the house unless you have other significant house construction issues (more likely would be pulled from the basement/crawl space).

*My concern is did you fix the leak problem of the HVAC?
White stuff in the drain pan under the unit indicates a long time condensate issue. Dirty coil, air flow restriction, refrigerant leak causing iced evaporator coil, or broken coil pan inside the unit?

Is there a float switch on the drain pan to shut off the unit when this stuff happens (not “If” but “When”?).

You have more potential costly problems than worrying about mold, which if not properly diagnosed and repaired will likely re-occur without your knowing and create that which you are scared of.

Thank you so much for the help with this!

The HVAC leak has been fixed and float switch was also fixed. I have been told this is likely the last summer our unit will be working due to the age and condition of it, but hopefully we have enough notice to save up before pulling the trigger on that.