Oh, mighty MB gurus!

My 1998 C280 is still having AC issues. I finally have some time to work on it today. I cleared the diagnostic codes and drove it for a couple of days to see what would come up. No new error codes have appeared. With the car parked, outside temperature measuring 83F and the inside set to 72F, I ran the dash AC diagnostics. The following are the readings with engine off and then with the engine on. Any thoughts on this one?

Also, does anyone have access to material that shows the correct amount of R134a that should be in this system?

ITEM - OFF - ON
1 - 110 - 109
2 - 92F - 93F
3 - 100 - 101
5 - 98F - 101
6 - 143 - 152
7 - 1'5 - 4'5
8 - 96F - 96F
9 - 50F - 50F
10 - 465 - 465
20 - 00 - 00
21 - 000 - 070
22 - 000 - 000
23 - 000 - 000
24 - 11.4 - 13.7
40 - 02 - 02
41 - 03 - 03
42 - 18 - 18
43 - 6-C = 6-C
50 - 100 - 102
51 - 72F - 72F
52 - 50F - 50F
54 OFF - OFF