A duct sensor is a device that is used to measure the temperature, pressure, and/or humidity of air inside a duct system. It is commonly used in air conditioning and heating systems to monitor the air flow and ensure the system is operating efficiently. The duct sensor is typically installed in the return air duct and is connected to a control system that monitors the air flow and adjusts the system accordingly. The sensor can also be used to detect any blockages or leaks in the duct system, which can help to prevent system failure. The duct sensor is an important component of any air conditioning or heating system, as it helps to ensure the system is running smoothly and efficiently. It is also an important tool for preventing costly repairs or replacements of the system.