Where is the low pressure fiting for ac on a 1977 corvette?

On a 1977 Corvette, the low-pressure AC fitting is typically located on the dryer/accumulator. The dryer/accumulator is usually found near the front of the vehicle, often on the passenger side, but its exact position might vary slightly depending on the specific model and any modifications. It's a cylindrical canister with several fittings. The low-pressure fitting will be the smaller of the two main fittings. It's usually a service port with a cap.