1–the party with a high pressure; 2–the party with a high pressure; 3–low pressure;
4–high pressure; 5–the party with low pressure; 6–the party with low pressure.
In air central air with coolant R-134a there are ports with "quick-detachable connections" adapters. Each adapter represents the plug with a female thread for system protection from hit of polluting impurity.
PERFORMANCE ORDER
1. Close both valves on highways.
2. Connect adapters of manometers to the relevant ports.
3. Manually tighten nuts of fastening of hoses of adapters.