Yes the unit's a 13AJN30A01 Value series. I wanted to keep it simple.
So..... Basically if it's not broken don't mess with it.
I do preventative maintenance on the unit, which includes cleaning the condenser and removing debris at end of the cooling season. A fin comb to straighten fins if needed.
Then cover the top with a piece of plywood on stand-offs so the box can breathe.
On a second note: When a systems not running (static), is all the refrigerant in the vapor/gas state? And only becomes liquid after compression and cooling in the condenser pipes? Or does some of the refrigerant stay liquid when the units off?
Looking from the top down you will see that air enters the sides, is drawn through the coil and out the top. You will also notice that 1 side has no coil and is blanked off. Another side has 1/2 a coil. Air is drawn through 230 degrees of the coil And 150 degrees of the coil has no airflow. As The blade hits the dead spot it chops the air and you will have noise.
It looks like Rheem uses the same box for the 13-seer 2.5, 3.0 and 3.5 ton units.
Just adding more coil area, fan and compressor size as needed.
Simplifies the amounts of parts needed on the assembly line.
But it does leave blank areas on the smaller ton units.