What is the problem of overbearing 2700 warm air being hot but not hot?

1 The passage into the heater tank is blocked, resulting in insufficient hot water entering the heater tank. Insufficient hot water will cause the water tank to be half hot and half not hot, and the wind blown out of the unheated air duct will not be hot either. The non-hot side air duct is not open or blocked, and the air outlet has a switch. Please check it.