hvacinsulation
I noticed the exterior on my AC units has small black circles and I assume it is mold. A few days ago the drain was plugged and the condensation all backed up inside the unit. I had the drain fixed but now the insulation has mold and pretty much falling apart. I want to replace them, what's the best way to do it.
Please see the pictures. Thank you.
You are correct that the refrigerant is not a consumable. If a system is low on refrigerant, then it has a leak. The technician should have a "sniffer" tool that can detect refrigerant leaks. If they didn't use it last time, then they were irresponsible. Also, refrigerant is expensive so that attitude of "if it gets low again then we know you have a leak" is wasteful of your time and money.
If the compressor in the condenser (the outside unit) is running and the air is not cool, then you are probably low on refrigerant. Frost on the refrigerant is also a pretty clear sign of low refrigerant.
I am additionally concerned about the condensation on your duct work. Is the air handler inside the conditioned envelope of the house? If so, that could explain the condensation you are seeing now but would not be seeing normally.
The Tee was left open as a means of a clean out.
Start by using a shop-vac on that Tee and hold your finger over the other end, in the pump (you may have to get the pump out of the way).
Next, snake it out, going into the machine: (e.g., the brush that comes with an EZ-Trap; johnstonesupply.com)
Followed with another vacuuming. Ideally the first go sucks it out; you don't want to just push the clog inside. If it still leaks after all that, you may have a cracked pan.
Best Answer
I've done similar repairs to AC units. The yellow insulation can easily be replaced with fiberglass insulation from your home store. It can be cut to fit and just set in place.
I would not be replacing the insulation inside the plenum as you would weaken the structure. I'd spray some white vinegar in it and let it dry. Vinegar is great for killing mold, surface and below the surface. Then lightly vacuum it out but don't break up the insulation. Make cleaning the drain a yearly task and don't wait for it to leak first. Many AC units have a safety float in the drain piping that will shut the unit down if water fills the pipe.