Question about Aprilaire 600 Humidifier

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Low Voltage to Solenoid


I am having trouble with my AprilAire 600. I originally thought that my solenoid was failing but I took it apart and it seems fine. I then used a multimeter to test the voltages across the different connections.

I found that the power from the furnace was coming in at 24V but the voltage going out to the solenoid and sensor were around 6V. I'm pretty sure the solenoid needs 24V in order to open. Any thoughts on why my voltage is coming out to the solenoid so low? I touched the solenoid to the contacts coming into the panel and the solenoid opened right up no problem.


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Re: Low Voltage to Solenoid

The controller is faulty. The previous question was hopefully to help determine why it faulted. The switching for the solenoid is a solid state device that is allowing the 6v through but not getting turned on hard enough to supply the current to operate the solenoid. I am assuming that you checked the voltage with the solenoid connected. If you disconnect the solenoid and look at the voltage it will probably be 24v. If you are not comfortable troublshooting down to the component level a new controller will be your best bet. It may be that the transistor that drives the solenoid could just be replaced. You would have to look at the signal that drives it to determine if it is being turned on with adequate signal.

Posted on Jan 18, 2008

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