I'm not an A/C expert by any means. I am planning on calling the pros to fix the issue, but want to be sure the initial information I give is at least accurate. My system has a refrigerant leak, to the point that the outdoor condenser is throwing a low pressure limit switch error (Bryant unit, blinking 32, which my lovely "reporting" sensing thermostat is not reporting because apparently my zoning system is blocking it, but regardless - initially I thought the indoor coil was the likely culprit because it is somewhat rusty and has some bent fins, but I was not able to see any oil like splotchiness on any of the fins (it is a cased N coil so I cannot really get to the outside of the left fins that well, but stuck a camera in there and didn't see anything on that one either.) I traced the line from the coil towards the outdoor unit, and saw that on the final bend, the wrapped pipe has what appears to be black oily substance covering it. Is this likely the point of my leak? Obviously there could be more than one, so they will likely need to leak test everything anyway, but am I at least on the right track here?
I don't have the finances to replace the whole unit right now, so I'm hoping I can get this repaired and hobble along for at least another year or two. My system overall is somewhat undersized for the house (2 ton unit, 2200 sqft in Iowa) so eventually I will need to upside, but hopefully not this month.
Thanks so much for your help!