O-Rings
Install new GM-approved service replacement air conditioning O-rings when a joint or a fitting is installed, except when the O-rings are provided on new replacement components. Unless service replacement O-rings of the specified part numbers are used, excessive leakage of Refrigerant-134a may occur. Refer to the part number for identification.
Air conditioning O-rings should be coated with polyalkaline glycol (PAG) refrigerant oil just prior to installation and should be slipped onto the flange pipe to assure proper locating and sealing. To prevent the possibility of swelling and a reduction in sealing effectiveness, O-rings should not be soaked in PAG refrigerant oil. Before installation, the O-rings and fittings should be examined to ensure that they have not been nicked or deformed. Nicked or deformed parts must be replaced to prevent refrigerant leakage.
Important
^ Keep PAG refrigerant oil off fitting threads. Long term contact of oil on threads may cause future disassembly difficulties.