Aprilaire 760 peoblems

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Old 12-01-07, 01:40 PM
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Aprilaire 760 peoblems

I have an Aprilaire 760 and the fan doesn't work and I have no water flow to the evaporator pad. Cycling the humidastat while the furnace is running, I hear a slight click at the water valve. Checked the strainer on the outlet side of the water valve and it's clear. Is there possibly a bad relay or something or do I have 2 seperate problems?
 
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Old 12-01-07, 03:06 PM
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What happens when you "short" the two brown wires coming off the humidifier?
 
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Old 12-01-07, 04:38 PM
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Similar problem

I also have an Aprilaire 760 that worked fine last this year. I changed the filter today and turned the humidistat up so that it clicked but the motor did not turn on and no water flowed. I am not sure where to start to diagnose the problem. I did check the outlet that it is plugged into, and it is working. What connections should I try to jump first, and what should I be jumping them with? Any help is appreciated.
 
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Old 12-01-07, 04:41 PM
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There should be two brown wires coming out of the humidifier, it may be wire nut with a wire going to the humidistat...

You can undo the wire nut, and just touch the two wires by hand and see if it starts.

does your humidistat have "TEST" on it? if you do, turn it over to test first and see what happens before you undo the wirenut.
 
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Old 12-01-07, 05:20 PM
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I disconnected the wire nuts and connected the brown wires together and nothing happened. Also, the humidistat does not have a test button. What would you suggest next?
 
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Old 12-01-07, 09:46 PM
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Since you've touched the brown wires, sounds like it's the humidifier itself.

Do you have a meter?

Pop the cover off the unit, and take a reading to 120v on the left. If you are reading power there, then read at the 24v humidistat on right..

If you got power to the 120 on left, and nothing on the 24v then you got a bad transformer. Need to replace the board.

Ifyou are not getting 120v to the board, then cord is bad, or don't' have power in the outlet.

http://arnoldservice.com/Aprilaire%2...close%20up.JPG
 
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Old 12-03-07, 03:28 PM
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Here's the latest:
1. Meter is out for the count.
2. Where the wires from the humidistat, furnace and humidifier meet, removed the wirenuts and jumped across, the water valve opened (but no fan)
3. Removed the cover on the humidistat and jumped across the 2 terminals, nothing happened.
4. Removed the front cover of the humidifier (the fan is mounted in the cover) and on the right of the cover there is 4 male connectors (4 females on the base unit) and jumped across 2 terminals and the fan came on.
So, it looks like the fan and the water valve are operational, jumping across the humidistat did nothing so I assume the humidistat is good. That leace the relay in the furnace and the electrical what ever it is in the front coner as possibilities. Any ideas>
 
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Old 12-03-07, 05:25 PM
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Jay,
I got a meter and tested the 120V power (the lower ones where the power cord comes in) and the 24V to the humidistat. Both worked. What would you suggest next?
 
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Old 12-03-07, 05:32 PM
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Originally Posted by denniskrup View Post
2. Where the wires from the humidistat, furnace and humidifier meet, removed the wirenuts and jumped across, the water valve opened (but no fan)
What wire? The two brown wires from the humidifier?
3. Removed the cover on the humidistat and jumped across the 2 terminals, nothing happened.
The HUM one?


Where is the 24v wire wired to on the furnace?
 
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Old 12-03-07, 05:34 PM
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Originally Posted by dakreeger View Post
Jay,
I got a meter and tested the 120V power (the lower ones where the power cord comes in) and the 24V to the humidistat. Both worked.
Both worked? You mean you have power there?..

What would you suggest next?
Being that you've touched the two brown wires earlier, nothing happens, and you are getting power at both place I've suggested, sounds like the relay board on the humidfier needs to be replaced.
 
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Old 12-03-07, 05:54 PM
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When I wrote that both worked, I meant that there was a reading of 120V on the power cord side and a reading of 24V on the humidistat side. Since I wrote I went back and on the wiring harness that is coming from the fan side, I jumped where the brown wires connect to the harness and the fan turned on. But when I install the fan housing to the furnace, the motor doesn't turn on. It seems that the connection isn't being made between the two. Any suggestions on how to test this theory and if it is the problem any suggestions on how to them to connect?
 
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Old 12-03-07, 06:11 PM
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Dak, I've never been around these units, so I don't know if there is a "door" switch on the unit?
 
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Old 12-03-07, 06:23 PM
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No, there isn't a door switch. Just the wire harness on the fan side with 4 wires (2 for the humidistat and 2 for the solenoid) and the corresponding wire harness on the furnace side.
 
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Old 12-03-07, 06:59 PM
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I am wondering if something is coming undone when you put the unit back together?
 
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Old 12-03-07, 07:36 PM
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Sounds the same as mine. A 44 prong male connector on the removable front cover and a 4 prong femal connector on the base unit. I was trying to figure out how to check if they connection was being made when you installed the front cover to the base.
Wiring. Mine has 2 brown wires coming from the base unit, 2 from the furnacce and 2 from the humidistat. The 2 wires from the water valve go into the base.
 
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Old 12-03-07, 07:41 PM
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Sorry, I meant 4 prong. Fat fingers here.
 
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Old 12-04-07, 09:22 AM
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Maybe Ed can help out here. I've never been around these unit to know how the wires make connections.
 
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Old 12-04-07, 11:01 AM
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Sorry...who's Ed?
 
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Old 12-04-07, 11:06 AM
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Originally Posted by denniskrup View Post
Sorry...who's Ed?

He's another member on the board.
 
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Old 12-04-07, 01:19 PM
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Wink

Oh Boy here we go. We sell and install the 700 all the time . CAUSE we have not had any trouble with them at all. Clean and put a new pad in is all. I asked all the guys and not one has had to go work on a 700 cause it didnt work.
Now you can try http://www.aprilaire.com/themes/aa/en/manuals/400.pdf

Is the control board for it good ??? Does it get 24 Volts from the furnace??? If you have manual control not the OTS is the resistor case between 44,000 and 48,000 ohms??? Do get 24 Volts at the solenoid water valve??? You sure the door is on right and the 4 pins do go into the plug ok?? The transformer in it good.
Also look at http://estore.aprilaire.com/index.ph...ju2n72agq79cj3
They dont even say anything about more parts
Also do not leave in test mode as humidifier will not work after 1 min.
Then as Jay has been saying all along .You have to find out where you have 24V and 110V
I hope this helps
ED
 
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Old 11-27-08, 02:27 PM
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760 problem

I seem to be having the same problem with my 1995 model 760.
I work fine last winter. This year it would not run. I called a service tech and he concluded that the circuit board was bad.
I put in a brand new circuit board bu I still get no water valve opening and no fan.

I am getting 24 v from the humidistat into the unit and the 120 volt connection is live when the furnace fan is running.

I there some way to check the relay on the circuit board??

Any other suggestions would be appreciated.
 
  #22  
Old 11-28-08, 07:59 AM
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Originally Posted by PaulG View Post
I put in a brand new circuit board bu I still get no water valve opening and no fan.
I would contact them again, and tell them it's still not working.


I there some way to check the relay on the circuit board??
If you got both voltage to the board/relay, then it's a bad board.
 
  #23  
Old 01-27-09, 08:37 AM
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Can not locate the Aprilaire 760 humidifier control

Please pardon my obtuseness, but I can't seem to find the humidifier control for my Aprilaire 760. I just began renting this house and since the landlord is lazy, I find myself having to troubleshoot/fix this unit. If I wait for him to get around to it, the it will either be spring, then it will not be needed, or I will have bleed out from the dry air.
 
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Old 01-27-09, 01:00 PM
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Follow the low voltage wire from the humidifier and it should lead to a humidistat/control.

Lot of time they are mounted on the return ducts, and some times up by the t-stat.
 
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Old 12-16-09, 08:52 PM
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Aprilaire 760 problem

I am struggling with my Aprilaire 760 humidifier. Water runs fine, but the fan does not come on. I opened up the front cover and read 24 V on the right hand side of the control panel between the two brown wires and no voltage between the two yellow wires. Is this normal?

I jumped the same two brown wires, but no fan comes on. Does that mean I have a bad motor for the fan?

Any ideas for testing will be appreciated.
 
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Old 12-16-09, 09:11 PM
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If the water comes on, then you may have a bad motor.

Check for power going to the fan motor.. If you have power going to the motor, then it's bad.

if you don't read power, may have a bad relay.
 
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Old 01-03-10, 11:01 AM
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What if Fan & Water Only Come on When Crossing Wires?

I crossed the brown wires and the fan and water came on. So, does that men that the problem is identified?

What do I do now?
 
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Old 01-03-10, 06:25 PM
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If everything came on when you touched the two wires, then trace that wire to where it's going to.. I"m guessing the humidistat?
 
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Old 11-03-10, 07:21 PM
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Aprilaire 760 runs all the time

I have an Aprilaire 760 that is I think about 17 years old. I've solved one of two problems but need help with the second.

The first problem was that water to it would run all of the time (even when the unit was disconnected from all sources of power). I fixed that by putting in a new solenoid valve. I think that valve was bad for at least the last 3 years. (I bought the house 2 years ago & I don't think it ever worked).

The second problem is that the Humidifier doesn't turn off when the furnace does. This is a new issue this heating season (I think).

When I first plug in the unit, everything is off. When the furnace starts, water starts flowing and the fan on the humidifier starts. When the furnace fan shuts off, the humidifier stays on (both the fan and the solenoid valve).

Thanks in advance for any troubleshooting suggestions.
 
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Old 11-03-10, 07:27 PM
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What is used for the humidity control?

Is the control tied to the furnace control board, or a switch (Sail or A50) of some type is used?

Has the humidifier ever shut off, or been stuck "ON" since?
 
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Old 11-03-10, 07:52 PM
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Thanks for your quick reply.

The humidity control is an old style analog humidistat. (a box on the wall next to the thermostat). I've not played with that yet. That's on my list of things to do tomorrow. Its Miller time here now

I'll also look at how its connected to the furnace tomorrow if I have a chance. The furnace is a brand new Goodman. The installer mentioned that it has a relay between the furnace controller and the humidifier but I need to look and see how it is set up.

Now that I think of it, the humidifier never came on last winter (that I could tell). I replaced the furnace this summer so the installer may have set something up different.

I may get sidetracked tomorrow. I have a grandson due at any time and will be leaving to visit my daughter's house (18 hours away) tomorrow or the day after.

Lorne
 
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Old 11-03-10, 07:54 PM
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Enjoy your miller and new grandchild!

Come back when you have a chance, and I'll help ya out. Also, post back the model # on the furnace too when you come back here.
 
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Old 12-29-10, 10:21 PM
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REPLACED AN OLD APRILAIRE WITH A NEW ONE, BUT IT DOESN'T WORK

I just replaced an old humidifier, April-aire Model 760 (beige housing), with a new 760 M (gray housing). The old unit was installed in October 1997 and was literally falling apart. For example, the motor board / bridge plastic started crumbling and I think the circuit board got fried by exposure to moisture. I was going to start replacing the bad parts, but decided to bite the bullet and invest in a new humidifier.

The good news is that the housing fit perfectly in the existing opening on the heater plenum. The new (manual / analog) humidistat also fits nicely into the same spot on the cold air return as the original humidistat. And since the water supply and solenoid valve are in the same place, there were no plumbing issues. So far, so good.

But the wiring has turned out to be a problem. I thought the wiring on the new unit would be set up the same as the old one, so I simply swapped every existing connection with the corresponding wire on the new humidifier. But the unit does not work. The solenoid valve is not opening and I do not think the fan is running. I don't think it is getting the required 24 VAC power it needs from the furnace, which was originally set up with a relay that would turn the humidifier on whenever the blower fan was running.

To make matters a bit more confusing, the new humidifier came with a 120 VAC to 24 VAC transformer that I did not install, mainly because I thought the existing set-up within the furnace would provide the 24 volts needed to power the solenoid valve and trigger the fan relay.

My family has been getting sore throats and sinus congestion since the weather turned cold, most likely due to the low (to no) humidity in the house. So I would really appreciate any advice about how to make this new unit operational.

Thanks in advance to any and all who might help with this question!

Tony
 
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Old 12-30-10, 06:24 AM
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Where did the low voltage wire from the unit go to on the old unit?

The new and old unit are not the same wire hook up.
 
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Old 12-30-10, 01:16 PM
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Replaced an old aprilaire with a new one, but it doesn't work

Thanks for the prompt reply, Jay!

The old (beige) humidifier had 4 wires exiting from the lower right-had corner of the housing, 2 yellow leads going to the solenoid valve and 2 brown leads that were attached via a 4-foot extension wire (brown sheath with a red and white lead inside) to the humidistat. However, on my existing set-up the red lead is cut and the 2 cut ends are wire-nutted to 2 yellow leads that go inside the furnace, into the blower motor housing, to a Model 50 relay that is supposed to sense current from a heavy white wire (to which it is tethered) going to the blower motor, so that the humidifier only runs when the blower is running.

The new (gray) humidifier is set up with the same 4 wires exiting the housing in the right-hand lower corner. Again, the 2 yellow leads go to the solenoid valve and there are 2 brown leads, stripped, tinned with solder and the packaging included 2 wire nuts, which I had assumed was to connect these 2 brown leads to the humidistat.

Interestingly, the box the new (gray) humidifier arrived in had a red and white tape running across the top indicating: "Attention - New recommended wiring diagram inside carton"

Now, what is weird is that the sheet they are talking about specifies that one of the 2 brown wires exiting the housing on the lower right-hand corner should be run to a constant 24 VAC source and the other should be connected to one of the terminals of the "MHC" (manual humidifier control) - do they mean the humidistat?? But they also specify that this same pair of brown wires be spliced to a pair of wires (white/yellow and white/blue) coming off of an Aprilaire 4851 relay (blower activation relay).

There is no mention of the Aprilaire #50 Relay installed in my original setup. And they do not specify if the 24 VAC / 10 VA transformer they supply should be used to provide the constant 24 Volts AC that these "wiring recommendations" specify.

The bottom line is that I do not think the new gray Model 760 is getting any 24 VAC power and I think I need to use that supplied transformer to provide it. I think that the Model 50 relay in my heater is purely intended to ensure that the humidifier only runs when the blower is running. The question is how to wire it into the circuit with the new (gray) Model 760. I also think that the "wiring recommendations sheet" is incorrectly specifying use of the Model 4851 relay, which by my reading, is intended to make the blower motor run when the humidistat calls for humidification, which I do not need or want.

Sorry for the long-winded reply! I hope this answers your question.

I would value your thoughts.

Thanks, again.

Tony
 
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Old 12-30-10, 01:33 PM
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What is the make/model of your furnace? We may not need the transformer.
 
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Old 12-30-10, 04:41 PM
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Replaced an old aprilaire with a new one, but it doesn't work

Hi Jay:

My furnace is an "Amana Air Command 90 - Dual Certified Venting - High Efficiency Gas Furnace.

Thanks,

Tony
 
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Old 12-30-10, 06:11 PM
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I need a full model # from the unit.
 
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Old 12-30-10, 08:15 PM
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Hi Jay:

The model number is GUD090X50B. The label is stuck on the inside of the housing up in the upper left-hand corner and is partially hidden by the vent pipe (PVC), so the entire label is very difficult to see. I think there may be more to it, but let me know if what I have given you is sufficient.

Thanks!

Tony
 
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Old 12-30-10, 08:23 PM
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Your furnace has HUM on the board, that is 120v.

We need to wire the transformer onto this.

Before I go into the humidistat, what model # is the humidistat did you get with your humidifier?
 
 

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