Volkswagen Passat 1995 Official Factory Repair Manual page 4194

A/C refrigerant system, servicing
http://ebahn.bentleypublishers.com/vw/servlet/Display?action=Goto&type=repair&id=VW.B4.HA01.87.5
Always flush components in opposite direction
of refrigerant flow.
Flush evaporator through the low-pressure line
with the high-pressure line removed.
If any component has dark thick deposits that
cannot be removed with compressed air,
replace component.
Thin light gray deposits in refrigerant lines and
hoses are normal and do not impair the function
of the system.
Always replace receiver drier and restrictor after
flushing.
Dispose of contaminated refrigerant (PAG) oil
following laws governing hazardous waste
disposal. Do not combine PAG oil with any
other old oils such as engine oil or transmission
fluid.
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12/7/2004