When a humidifier doesn't run, it generally means it isn't receiving electrical power or the controls have automatically shut it off.
1) Be sure it's plugged in to an outlet that works and that it's turned on. Check the electrical receptacle for power, using a working lamp, appliance, or voltage tester.
2) If the receptacle seems to be dead, check the circuit breaker or fuse that serves the humidifier's circuit.
3) Check the setting on the humidistat. If it's set lower than the room's relative humidity, the humidifier won't go on; in fact, it may take several hours for the humdistat to respond to the room's changing humidity.
4) Be sure the humidifier's reservoir is full of water.
5) Unplug the humidifier unit.
6) Check the power cord. If necessary, repair the cord.
7) Remove the humidifier's cover panel.
8) Remove the humidistat and check it (as shown below). Replace it if necessary.
9) If it still doesn't work, call an appliance repairperson, take the unit into an appliance repair shop, or replace the unit.
To check the humidistat, you?ll need a volt-ohm meter.
A humidifier?s fan vaporizes the water in the reservoir and blows the water vapor into the house or room. If you need to check the fan, unplug the humidifier, remove the control panel, and lift the lid. Tighten the fan hub with pliers if it is loose; this should take care of rattles. If the fan doesn?t spin easily when you try to move the blades by hand or if it is still noisy, lubricate the motor bearings with oil.
To establish whether power is reaching the humidistat when you know there are no problems with the plug or switches, unplug the humidifier, remove the control panel, and lift the lid. Test it with a volt-ohm meter set to the RX1 scale (or to K[omega symbol] or [omega symbol] resistance on a digital meter). Clip the meter to the humidistat terminals. The meter should jump if you turn the humidistat from high to low. If it doesn?t, you?ll need to replace the humidistat or return it to the manufacturer.