Where is the low pressure port on my 2006 Chevy trailblazer?

The low-pressure port on your 2006 Chevy Trailblazer is located on the larger diameter aluminum line, typically near the firewall on the passenger side of the engine bay. It is usually covered with a plastic cap, which you can remove to access the port for adding refrigerant or checking pressure. Be sure to identify it correctly to avoid confusion with the high-pressure port, which is smaller and on a different line.