Unfortunately for homeowners black mold also loves air vents where spores are naturally circulated.
Mold in air handler insulation.
Enough of that moisture was transported to the air handler to saturate the fiberglass insulation.
Leaks out of the air handler can also damage surrounding building components such as drywall or insulation.
Mold spores naturally traveling in the air attach to damp areas then begin to grow.
Mix 1 quart of liquid chlorine bleach with 3 quarts of warm water and add 1 3 cup of powdered detergent.
Mold typically does not grow on metal glass and plastic.
It turned out that the system have a refrigerant leak and the leak meant the system was running almost continuously and producing a lot of condensate.
Air conditioner air handler rust condensate leaks wet insulation mold hazards leaks in the air handler can cause rust damage and may invite mold contamination in the ahu or in the hvac system ductwork.
You could also use an insulating hvac paint they use on ducts.
I often find mold on the exterior of air conditioning systems more often than the interior.
Wear rubber gloves since bleach.
Mold is common in environments that have dirt dampness and darkness.
This is typical if you find condensation or microbial growth around the air handler joints connections to ductwork to the plenum.
In some cases the air handlers simply are not insulated well enough in areas.
Simply put add more insulation.
The outside of ducts more often than inside.
How to remove mold from an air handler.