K 3500 Truck 4WD V8-454 7.4L VIN J SFI (1996)
A/C Coupler O-ring: Description and Operation
This vehicle uses GM's dual O-ring joint design in the system. This design increases the durability of the joint seal by providing a second O-ring seal.
The dual O-ring design consists of:
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An aluminum-alloy, externally threaded fitting which is brazed or welded to an aluminum tube.
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A free-spinning, plated steel internally threaded nut.
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A precision machined, male-piloted aluminum tube end which accommodates two O-rings.