I have a Lasko 5000L whole house humidifier. This year I forgot to power it up until this past week. The house just felt oddly cold and the usual symptoms of low humidity were there like dry hands. I checked my house humidity and it was at 25%. Yep, pretty low.
So I powered it up, and checked to make sure it was working properly. The setup is pretty simple. It has a humidity sensor in the return duct of the furnace. That controls power to a solenoid valve that flows air over a mesh in the ducting. When the furnace is running, and the humidity is too low, the solenoid opens and adds water to the air. I heard the solenoid clicking, but I didn't hear any excess water draining out of the bottom of the unit and into my basement sump. So, I opened it up, and sure enough, no water was flowing. I played around with the control a bit more. The solenoid was going, but still no flow.
I didn't really get pictures as I just wanted to get the job done. Here is one of the solenoid on the side of the machine.
Alright, time for fix it mode. I removed the solenoid valve from the unit. This was just two screws and two blade connectors. I shut off the water to the unit and removed the tubes going to and from the solenoid. I then took it and sat it in a cup of white vinegar overnight. The vinegar only soaked the mechanical part of the valve, not the electronic part. I occasionally swished things around and could see flakes of white and brown come out of the valve. Not a ton of junk, but some. The next day, I flushed the valve with water in the sink and hooked it back up and presto bango it was flowing water again. Nice simple fix to a little problem.