First read and observe the introductory information
and safety warnings
Volkswagen recommends the use of genuine Volkswagen spray with lubricating and anti-corrosive properties to de-ice the lock cylinders.

NOTICE
Care of rubber seals
UndersealDischarge Refrigerant Circuit with A/C Service Station
Caution
If it is suspected that chemicals were added to the
refrigerant circuit to seal leaks, do not connect the
A/C service station and do not extract the refrigerant.
...
Test Requirements
Radiator and condenser are clean (clean if necessary).
The ribbed belt for the A/C compressor and alternator
tensioned correctly.
All air ducts, covers and seals are OK and installed
correctly.
...
A/C Programmer -J127
This programmer switches the refrigerant flow direction
through the second evaporator if the temperature on the cooling
fins on the second evaporator lowers to the freezing point for
water (icing protection).
...