aprilaire humidifier model 440 help needed

Old 01-13-08, 09:57 AM
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aprilaire humidifier model 440 help needed


I have a aprilaire humidifiermodel 440 with a York Electric furnace model 3HL06502006D. The humidifier isn't working. With furnace running and humidifier turned all the way up, there is No water running into the humidifier. What is the order of things I should check to diagnose the reason it is not working? I know that the solenoids are commonly the problem with these units, so I attempted to check that the solenoid had power coming to it, but I'm not sure still not sure if it has power coming to it or not. I used a 60-500 VAC/DC test light and with the furnace running and the humidistat turned all the way up, I conected the test light to the 2 wires going to the solenoid and the test light did not light up. I'm not sure though, if a 60-500 VAC/DC test light is the correct way to test for power, because I read somewhere that this humidifier only used 24 volts. So, any help with diagnosing why my humidifier doesn't work would be much appreciated. Sincerely mross
Old 01-13-08, 07:17 PM
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Yes, you are going to need to get a multi meter that can read 24 volts.

If you are not getting any clicking noise, go to the humidistat, and jumper the two wires together, and see if you get anything on that.

otherwise, find the power source where the humidifier is getting it's power from. Make sure no cut/broken wires, and good connection to the transformer.

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