A/C Programmer -J127-
WARNING: This page is about a different car, the 2010 Volkswagen Passat and 2009 Volkswagen Passat. However, it is still accessible from the selected car via links, so may be relevant.
Courtesy of VOLKSWAGEN UNITED STATES, INC.
This programmer switches the refrigerant flow direction through the 2nd evaporator if the temperature on the cooling fins on the 2nd evaporator lowers to the freezing point for water (icing protection).