My E320 was stuck in EC mode (light on) and thus could not get AC to work.
I found several related topics explaining how to obtain the on-board diagnosis codes via N22 control module on benzworld.com and mercedesshop.com forums as well as http://www.continentalimports.com/ser_ic40142.html and http://www.eclassbenz.com/acdiag

01: 98 in-car temp
02: 76 outside temp
03: 69 heater-core temp left
04: 69 heater-core temp right
05: 73 evaporator temp sensor
06: 66 ECT sensor
07: 04 refrigerant pressure
08: 67 refrigerant temp sensor

I also got the following Faulty codes:

EB1419 electromagnetic clutch
EB1234 sun sensor (safe to ignore based on read articles)

I then followed the instructions posted by Sokoloff (MB bulletin 37/99-2) and could turn off the EC mode:
http://www.peachparts.com/shopforum/showthread.php?t=86110

I have not yet replaced the evaporator nor the refrigerant temperature sensor at this point. My AC is still not blowing cold air though.

The faulty electromagnetic clutch code EB1419 does not sound like a simple problem to me. So, before replacing any unnecessary parts, just wonder if any MB tech gurus here can point me to the right direction?

Appreciate much your inputs...
John

__________________
Tigger - 2001 E320