Where is the low-side port on a 1988 Chevy Silverado K1500?

On a 1988 Chevy Silverado K1500, the low-side port for the A/C system is typically located on the accumulator/receiver drier. The accumulator/receiver drier is usually found near the firewall, on the passenger side of the engine compartment. The low-side port is smaller than the high-side port.

However, the exact location might vary slightly depending on specific options and modifications to the vehicle. It's always best to consult a repair manual specific to your 1988 Chevy Silverado K1500 to be absolutely certain. A visual inspection with the hood open will help you locate the components.