What is the reason why warm air is not hot?

Land Rover found that the reasons why the warm air is not hot are: 1, the warm air pipe is blocked or extruded; 2. The heater damper motor is not converted; 3. The control water valve in the system is out of order. Take Land Rover's Range Rover as an example: its length, width and height are 5000mm, 2073mm and 1869mm respectively, and its wheelbase is 2922 mm It is equipped with an 8-speed automatic manual transmission with a top speed of 209 kilometers per hour. Range Rover fuel tank volume 104L, maximum torque of 495 Nm, and maximum torque speed of 2000-5000 rpm. The driving mode of the car is front four-wheel drive, the front suspension is double wishbone independent suspension and the rear suspension is multi-link independent suspension.