Humidifier filled with water, but red light is on

If there is a lot of scale and mineral deposits , you can run a 50/50 solution of White Vinegar and water thru it, by half filling the tank with the solution. When it's almost empty, turn it off, empty the remainder of the solution and flush the system with clear water. In the future I recommend that your use bottled Distilled Water, instead of tap water.

There is probably a calcium buildup in the lines from the tank to the humidifier. You will need to take it apart to lean it. 50/50 White Vinegar should do the trick, Then flush the system with clean water, before using it as a humidifier again. In the future try using Bottled Spring Water or Distilled Water instead of tap water. Especially if your source of water is a well.

From the troubleshooting section of the manual (http://www.crane-usa.com/manuals/HumidifierManual2008.pdf):
Problem Humidifier power light is staying red and not turning green Humidifier is working than stops: ? Solution Ensure that water level sensor is assembled properly. ? Clean water float ? Call service center and request replacement water float ? If humidifier does not work at all: ? Ensure it is properly plugged into a power outlet. ? Check that the switch is in the ON position. ? If Power On indicator light does not come on, bring to authorized service station.

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• Ensure that the water tank cap is secured properly to water tank.
• 
  Empty out water in water basin. Place filled water tank on to empty water basin.
• 
  Clean Water Level Sensor.

Hope this helps!

there will be a water level sensor at inside wall try to fix it .it also seem to be a power failure case well since you have just got it must in warranty or free service utilise it.
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FROM TROUBLESHOOTING SECTION OF MANUAL:
Humidifier power light is staying red and not turning green Humidifier is working than stops: ? Ensure that water level sensor is assembled properly. ? Clean water float ? Call service center and request replacement water float

The red light indicates that there is no water in it. You need to put water in it, then a green light comes on instead. When the water runs out you will see the light turn red again. You need to fill it about 2/3 - 3/4 of the way up to make it last.  You should refill it about once a day or every 2 days depending on how often you use it. But when you see the red light on then you know the water is gone. 

According to the Crane's Troubleshooting section:
The power light is green but there is no mist being emitted:
- Check that there is water in the tank.
- Check for possible lime deposits on the water level sensor or the nebulizer.
- Make sure that nothing blocks the vapor output slots.
- Check that the fan vent on bottom of humidifier is not blocked.
- Empty the humidifier and rinse the water basin with cool tap water and allow to dry for 15 to 30 min.

This next part may or may not be relevant.
Humidifier power light is staying red and not turning green. Or, Humidifier is working then stops:
- Ensure that water level sensor is assembled properly.
- Clean water float.
- Call service center and request replacement water float.

Barring that, here is the service center contact info:
Dart Warehouse Corporation
Tel: 1-888-599-0952 (Business hours Mon-Fri 9:00 am - 4:00 pm Ct)
Website: http://www.crane-usa.com
1835 Ferry Road
Naperville, Illinois 60563

if humidifier was wired into thermostat circuit for power instead of seperate transformer , this can happen. you need to see if you voltage going to the solenoid valve. if you do , and it isn't opening, the valve is bad . this is assuming that it is using a # 50 relay to come on only when the fan runs . . make sure the water valve is open