If your vehicle is showing no air coming from vents at all, here are the most likely causes and the parts you'll need to fix each one.
The electric motor responsible for pushing air through your vents has worn out or its bearings have seized. This is a common wear item that eventually fails after years of use.
This component controls the fan speed. While it typically fails by leaving only the highest speed working, a completely burnt-out resistor or a melted wiring connector will stop all airflow completely.
A fuse protects the blower motor circuit from electrical overloads. If the blower motor starts failing and draws too much power, it will blow this fuse and cut all power to the fan.
The relay acts as a heavy-duty electrical switch that provides main power to the blower motor. If the internal contacts burn out, the motor won't receive any electricity to turn on.
If the cabin air filter was installed incorrectly, crushed, or left out during recent maintenance, leaves, debris, or even rodents can enter the blower motor cage and physically jam the fan from spinning.
The physical dials or digital climate control unit in your dashboard may have failed internally, preventing the 'turn on' signal from ever reaching the blower motor circuit.