The low air volume may be caused by motor failure.
1, check the exhaust fan switch, and measure it with an electric pen or multimeter. If it is broken, replace it with a new switch.
2. Check the wiring of the ventilator, separate the thread ends of the exhaust fan, carefully check whether the thread ends fall off, or whether the thread ends are welded in white, find the thread ends that fall off and bind them with electrical tape.
3. If it is an exhaust fan that has been used for several years, it is likely that the rotor has accumulated dust. Check it and remove it.
4. If the above inspection method is invalid, it means that there is something wrong with the motor and it can only be repaired.
It can also be replaced with a high-power one, and you can consider updating a high-power one if conditions permit.