The service port is the access point on the outdoor unit where a technician connects their Manifold Gauge Set. This allows for the measurement of system pressures and the addition or removal of refrigerant. Most of our Cooper&Hunter units use a 5/16" service port, which may require a 1/4" to 5/16" adapter for standard hoses. You will find these ports on the Isolation Valves of the outdoor condenser. They are used during the Evacuation Process to pull a deep vacuum. Always ensure the service port caps are tightened after use to prevent slow leaks. For technical details on port locations, check the Technical Data for your specific model. It is the primary "gateway" for maintaining your system's health.