Location of the orifice tube in a 1999 Pontiac grand prix?

The orifice tube in a 1999 Pontiac Grand Prix is located within the high-pressure side of the air conditioning system, usually near the accumulator/receiver-dryer. It's not easily visible without removing some components. You'll likely need to consult a repair manual specific to your vehicle's year and model to pinpoint its exact location, as there might be slight variations depending on the specific AC system configuration. A shop manual or a reliable online parts diagram will be most helpful.