I live in metropolitan Houston, Texas (note: high humidity), and this concerns a home I recently purchased. I have a heater (furnace) and blower unit installed in the attic, which is typical for many homes in Texas.
I do DIY maintenance on our home, but I am not extremely familiar with A/C DIY. I noticed what could be a little mold forming on the outside of the box portion on the right. Edit: After doing some more research, I am almost certain that this section of the A/C unit is where the evaporator coil is located, as there appears to be two lines entering the top of the unit, one of which is a copper refrigerant line.
Here is a close up of the suspected mold (the drain pan, which also suggests the evaporator coil is located in this section of the A/C unit, is located on the bottom of the image):
I would like to inspect the inside of the evaporator coil box to perform maintenance and inspect for mold, but it seems to me that it is sealed by some sort of white sealant and a bit of duct tape (tape is not an issue, but the sealant is).
Do I just use a utility knife to cut the edges and open it up? And, if I do that and need to re-seal it, what do I use to do so?