A humidifier that is not turning on or is working poorly could be caused by many things. If the unit is receiving power but still not functioning properly, there are a few tricks you can try to get your humidifier working again.
Troubleshooting your General humidifier
Verify that the water tube feeding the unit is not clogged or disconnected. Unclog or reconnect as necessary.
Check the water trough to make sure it is correctly dispersing water over the evaporator pad.
Check the solenoid. This is a valve that is controlled by the humidistat and allows water to flow through the humidifier. Use a multimeter to check the number of volts. Solenoids operate via a 24-volt circuit. If you see the correct voltage displayed on the multimeter but the solenoid isn't allowing water to flow, the solenoid will need to be replaced.
Check the humidistat, which controls the humidity levels on the humidifier, by using a volt-ohm meter. To use the meter, set it to the RX1 scale. Attach the meter leads to the humidistat's terminals. Once the leads are attached, rotate the knobs of the humidistat as far as they will go in either direction. A meter reading of zero through the entire dial range means the humidistat is broken and needs to be replaced.
Make sure the evaporator pad is properly in place. Adjust if necessary.
Check the fan to see if it is working. Without air movement through the evaporator pad, the unit will not function properly.
Four humidifier parts that often need to be repaired or replaced
Evaporator pad—The evaporator pad, which is also known as the water panel or the water filter, is a permeable pad that is kept wet and through which a fan blows air to increase the humidity levels in the air.
Water distribution trough—The water distribution trough is fed by the water distribution tube, and it continuously disperses water over the evaporator pad to maintain the desired humidity setting in the room.
Water distribution tube—The distribution tube brings water to the water distribution trough and supplies the humidifier with the required amount of water.
Drain pan—The drain pan collects water that drips down through the bottom of the evaporator pad and drains it through the drain tube. If the drain pan is damaged or the hose clamp doesn't securely hold the drain tube in place, the faulty part will need to be replaced.