No easy tricks for getting to the coil. Doesn't appear to be any weight from above so you could cut a window then screw a patch over it when finished. What are the symptoms that make you say " I think may have clogged/frozen evaporator coils based on the symptoms."? And have you eliminated other possible causes?

Well, if your coil is frozen, opening it up may not be the solution. Let it melt and then first make sure you have a full charge of refrigerant and that the filter is clean (remove it for a couple of days to test the system). If it still freezes or doesn't cool/blow, only then would I consider breaking it apart.

"that the filter is clean (remove it for a couple of days to test the system)."

Dat rat da be bad vice,never run an ac without filter in place,not even for a few minutes.

save maybe $50 to $80 in a service call and create hundreds or more in possibly unnecessary repairs to duct work.

Sounds like the road to disappointment, if you ask me.

I would shut down the furnace for a few hours and see if water is draining to the floor drain and also check the drain line, it may be clogged. The other item without cutting up your ductwork, restart your furnace at a set temperature of 76 deg F or 24 deg C. People think that all units must operate at 72 deg or 22 deg. C, which is wrong, when I do the load calculation the design temp is 76 deg. F. I use to live in a 2 story house and to push the cooling to the second floor I closed my vents on the main floor, bathrooms and cooking area except for the living room and dining room and have the furnace run continuously. Placed a fan over the bedroom vents and had a fan operate in the kitchen on the main floor. Cool air is heavy and will drop to the main and have fans running on the second and main level. You want to operate a dehumidifier in the basement to remove access humidity. Humidity is always an issue in the summer as well as the cost of energy for operating the cooling cycle compared to heating.