Opening / Accessing the outside portion
I thought I would post this since I was not able to find much about opening up the exterior portion of these units. It is not actually complicated at all compared to what we have to do to clean the interior fan.
Some contractors were working on our building recently and I noticed quite a bit of construction debris sitting on the top of the exterior portion of the A/C while they were working. They cleaned it off when they left, but inspection with a flashlight through the side vents showed a brand new nail had fallen through the vents and was lodged in the fan blades at the bottom.
So it became necessary to remove the top cover in order to reach said nail with needle nose pliers and get it out of there.
The usual disclaimers apply: There are high voltages, moving parts, and sharp edges inside these machines. Don't open them up if you are not able to safely avoid injury from the interior. Be sure the unit is disconnected from the power before opening it.
I had to take the unit out of the window, but that was mainly because the window did not open far enough to reach in with the pliers and extract the debris. If you have a larger window or access from the outside you may be able to do this without taking it out of the window.
There are a total of ten screws that need to be removed to get the top cover off the exterior:
(2) on the left hand side at the top
(2) on the right hand side at the top
(3) along the edge of the top that faces the window. You will need a short screwdriver for these as the interior part of the U will be in the way. If you do not have a short screwdriver a socket wrench with a phillips bit in it will work as the screws are not super tight.
(3) on the top surface but not near the edges
Once all the screws are out the top cover actually lifts right off and is significantly easier than dismantling the interior for cleaning.
A few notes on reassembly:
The sides curve around at the far end and then end. It is possible to lower the lid on and have a portion of the side/rear be outside the lid; it may be necessary to tug on the sides a bit to get it in the right place. Check this before putting any screws in though; you do not want to discover after putting in 10 screws that they need to come out again.
The three screws in the top help keep some interior components aligned. Put them in first; you may need to push the top cover in one direction or another to get the holes to line up.
At least one mine there is some left to right play in the lid. So for the side screws, start them in the holes a couple turns, then go put the rest of the screws in, then come back and tighten everything down. This will avoid the lid pulling so far in one direction or the other that it isn't possible to get the screws in on the other end.
As all these screws are just going into sheet metal you'll get a better result if you start by turning them backwards until they click into the threads and then screwing them down.