A/C not cooling on my W210('97 E420). I did notice some hissing for a few days before it stopped cooling. When turning the A/C on I hear no compressor engaging and the auxiliary fans do not turn on. Here are the values:

1-30
2-30
3-37
4-37
5-23
6-80
7-00
8-29
9-05
10-3.0
11-4.3
12-2.9
20-0.0
21-06
22-00
23-00
24-13.5
40-71
41-36
42-00
43-136

When I pulled the codes it initially red :
E 1234 and 1235 which are sun and emission sensors,
but after a few minutes those were gone and all I had was E FF.

Any ideas? Could it just be low on refrigerant since there is no pressure?

Thanks!