F0 warm air is not warm, is it the small water tank?

F0 warm air is not warm, which is generally not the problem of the small water tank. It may be that the heater box is blocked and the coolant cannot flow through the heater box. The blower is broken, so it can't blow, bringing hot air into the car. The baffle in the air duct of the car can't operate freely, which makes warm air enter the car and blow out from the cold air duct, so it can't be heated.