The AC orifice tube on a 1996 Chevy Silverado 350 Vortec is located
within the high-pressure side of the AC system, typically near the receiver/dryer. It's not something you'll easily see without removing some components. You'll likely need to access it from under the hood, possibly near the firewall, but its exact position might vary slightly depending on the specific vehicle configuration.
Because it's a pressurized component of the AC system, you should not attempt to locate or replace it yourself unless you are a trained and experienced AC technician. Improper handling can lead to refrigerant leaks and injury. A professional mechanic will have the proper tools and safety equipment to handle this task.
