Ice formation on evaporator

Complaint:
the blower of the air conditioning system only delivers warm air after a long journey. Despite the high fan setting, the air flow rate is heavily reduced.
After parking the vehicle for a short time, the function returns to normal.

Cause:
formation of ice on the evaporator after a longer distance driven.
Effect is difficult to reproduce with short test drives.

Service:

In individual cases and after excluding other fault causes, the minimum value of the evaporator temperature can be raised from 0.8 °C to 2.4 °C.
This does not noticeably change the performance capability of the air conditioning system. The risk of the evaporator freezing over is significantly reduced.

Information on carrying out the repair:

• Vehicles with date of manufacture before March 2005:
  On these vehicles, the integrated heating / air-conditioning control panel must be replaced and reprogrammed. After programming, the change to the minimum value of the evaporator temperature must be made via coding of the integrated heating / air-conditioning control panel.
  As of version 26, Progman contains the necessary data. Entry via the path Modifications > Evaporator > Temperature > Raise or lower.
  
• Vehicles with date of manufacture March 2005 to November 2005:
  On these vehicles, the software of the integrated heating / air-conditioning control panel must be reprogrammed. After programming, the change to the minimum value of the evaporator temperature must be made via coding of the integrated heating / air-conditioning control panel.
  As of version 26, Progman contains the necessary data. Entry via the path Modifications > Evaporator > Temperature > Raise or lower.
  
• Vehicles with date of manufacture December 2005 to February 2006:
  On these vehicles, the minimum value for the evaporator temperature is stored in the integrated heating air-conditioning control panel.
  The value of the evaporator temperature is raised by means of the service function ”Evaporator control / operating parameters of the evaporator temperature”.
  The necessary data is on the Diagnosis and Information System DVD version 43 or later versions. Entry via the service functions at the menu item ”Evaporator control”.
  The change to the minimum value of the evaporator temperature cannot be reversed without part replacement.
  Before applying the changed minimum value of the evaporator temperature,the diagnosis software checks whether the change to the evaporator temperature has already been made.
  If the change has already been applied, ice formation on the evaporator has other causes.
  
• Vehicles as of date of manufacture March 2006:
  On these vehicles, the value of the evaporator temperature is not changed via the service function ”Evaporator control / operating parameters of the evaporator temperature”, rather by coding the integrated heating air-conditioning control panel.
  As of version 26, Progman contains the necessary data. Entry via the path Modifications > Evaporator > Temperature > Raise or lower.
  The change to the minimum value of the evaporator temperature can be reversed via coding.