Volkswagen Passat 1995 Official Factory Repair Manual page 4183

A/C refrigerant system, servicing
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A/C refrigerant system, replacing
components
Replacement A/C compressors, evaporators and
condensers supplied by the Parts Dept. are filled
with Nitrogen. If gas (Nitrogen) does not escape
when component is first opened, the component
may be faulty (leaking), do not install.
Replacement A/C compressors are filled with the
total refrigerant oil quantity needed for the entire
refrigerant system.
Always replace the receiver drier whenever the
refrigerant system has been left open. Install
immediately after opening to prevent moisture
contamination of drier desiccant. Moreover, keep
refrigerant system and other replacement
components sealed for as long as possible to
minimize the chance of dirt and moisture
contamination.
Always plug open refrigerant line connections to
prevent dirt and moisture contamination.
If the system has been discharged due to a
damaged or leaking component (refrigerant
hose/line, compressor, evaporator, condenser,
etc.), flush the refrigerant system first with
compressed air, then with nitrogen (available
locally) and collect the oil that runs out. This will
remove the refrigerant oil which may be
saturated with moisture.
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12/7/2004