A/C Coupler O-ring: Service and Repair

O-Ring Designs:

NOTE: While continuing to service with R-12, be sure to use "O" rings and seal materials which are compatible with R-134a and PAG oil. This practice will eliminate concern in case the vehicle requires retrofitting later in its life. All "O" rings and seal materials available from GMSPO are compatible with R-134a systems.


Install new GM approved neoprene service replacement air conditioning O-rings whenever a joint or fitting is disassembled, except when provided on new components. Even though an O-ring may look the same, it is extremely important that only recommended service replacement air conditioning 0-rings be used or excessive leakage of Refrigerant 12 may occur.

When replacing O-rings on an air conditioning component or joint connection, the fitting design should be carefully identified to ensure installation of the correct air conditioning service replacement O-ring. Some joint connections and components will implement a "captured" 0-ring design fitting that uses a groove to retain the O-ring, while others do not have a groove and use a "non-captured" or "standard" O-ring.

Assembly and tightening procedures are the same for both designs, however, the O-rings are different. Neoprene O-rings are color coated to ease identification and assembly. The following is a list showing the color applications for the currently serviced air conditioning O-rings:

a. Red-Captured (Grooved Male Fitting End Form) O-ring Design.
b. Blue-Non-captured/Standard (Straight Male Fitting End Form) 0-Ring Design.
c. Yellow-O-rings used on different types of Air Conditioning Switches.

These colored O-rings are available in various sizes for each application.

NOTE: Always slip the lubricated O-ring onto the flange tube to ensure proper locating and sealing.

Also, prior to installation, verify that both O-rings and fittings have not been nicked or deformed. Deformed or nicked parts must be replaced. Failure to use the proper service replacement parts and procedures may result in excessive Refrigerant. 12 leakage.