Aprilaire 760 Fan Not Working

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Old 12-20-17, 07:14 PM
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Aprilaire 760 Fan Not Working

Hello - First post here, long time lurker.

I noticed that the fan on my Aprilaire 760 was not working when the humidistat calls for humidification. But the water solenoid does work. I followed the troubleshooting advice on this forum, and thought I had it narrowed down to the control board. Ordered one, installed it tonight. Same issue. Ugh.

Here's what I know:

-The water runs when I jump the two brown wires going into the humidifier.
- I've got 26 volts across the humidistat terminals
- There are 24 volts going across the solenoid terminals.
- There are120 volts at the terminals for AC power in, but no power at the terminals for the fan.
- I direct wired the fan to 120 current, and it works.

Is it possible I have two bum control boards? Or did I miss something in the troubleshooting process? Thanks in advance!

Edit: I don't think it's related but this summer I did change from an old style humidistat on the wall to an Ecobee with integrated humidistat. It seems to be working since it's triggering the humidifier and water runs. But is one variable that's changed, so I thought I should at least mention it.
 
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Old 12-20-17, 07:32 PM
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Welcome to the forums.

Since you jumpered the humidifier wires together and it ran... you have a full powered unit.
When the humidistat is not calling for humidity.... there will be 24vac on the contacts.

Your h'stat is not the problem. It's the same as jumpering the two wires.
If you jumper the wires.... the relay should click.... the solenoid and the fan should operate.

Which board are you using ?
Is it this one..... if not let me know its part number.
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Old 12-20-17, 08:30 PM
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I ordered a Aprilaire 4238. What I got is pictured below, what I took out of my humidifier looked like your pic.

I'm not sure if what I received was an older version of the board, or if something else is going on. It was packed in a Aprilaire box, but the padding was crumpled up printer paper. I didn't even start thinking about it till you posted the pic. But it seems odd

 
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Old 12-20-17, 08:37 PM
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Apparently it's not liking my picture. Anyway, the Layout is the same but the board PCB is yellowish, the transformer is yellow, not black, and there isn't the research products group label on it like in your pic,
 
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Old 12-20-17, 08:37 PM
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Try posting the pic directly to the board... How-to-insert-pictures
 
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Old 12-20-17, 08:48 PM
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Trying the picture again. Fingers crossed!
 
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Old 12-20-17, 09:11 PM
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Great.... do me a big favor.
Flip the board over and shoot a second picture of the bottom for me.
 
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Old 12-21-17, 03:40 AM
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Here you go. Sorry about the delay. Fell asleep in my chair!
 
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