Use the info in this link to see what fault codes may be stored...
http://pages.prodigy.net/jforgione/MB_AAC.html
Also, per a friend who had this problem..."The document number for the climate control module in WIS is AF 83.40-P-6001 DA, you will notice that the required code Q 62 is the defective software produced by MB. In this case a new part number with the code other than Q62 should be installed"
Hope this helps.