Air-O-Swiss is an upscale brand of humidifier that creates a fine water mist, instead of blowing air through a wick. Unfortunately some models are prone to problems. One problem a number of people have encountered is a humidifier that no longer produces any mist (e.g., here).

If you have an AOS 7144 or similar model that no longer produces mist, and your warranty has expired, Air-O-Swiss may tell you there is no solution and you have to purchase a replacement. If so, don't give up hope! It is possible to revive a non-working humidifier and get it to produce mist again. This Instructable explains how.

Note that this Instructable assumes a moderate skill level. You should be comfortable using hand tools and a soldering iron, and be able to disassemble and reassemble moderately complex equipment. Opening up your humidifier will probably void your warranty, but if your unit is under warranty you probably wouldn't be here in the first place!

While making this repair and using the repaired unit isn't a dangerous activity for a moderately skilled person, obviously I disclaim all liability resulting from your use of these instructions. I can't be responsible if you burn yourself soldering, or if your unit ends up catching on fire, etc. Proceed with caution, and if you're not confident in your ability, seek the help of a qualified person.

Step 1: Gather the Required Tools and Parts

Items you are unlikely to have on hand are in bold.

You will need:

  • A Torx security bit (my set of security bits is shown in the red box in the photo) ($5 to $10 for a set)
  • A Phillips head bit
  • A soldering iron (Radio Shack's $10, 25 watt model is more than adequate)
  • A small amount of solder meant for electronics ($2 to $5)
  • A replacement 1 amp, 250 volt fuse (yes, 250V, even for U.S. 120V models) ($1.50)
    • If you plan to replace the existing board-mounted fuse, it is an OR5 1A 250V fuse with radial leads.
    • However, I recommend replacing it with a standard glass fuse. In that case, you will also need:
  • A fuse holder that accepts the size of replacement fuse you are using ($2 to $3)
  • Superglue or another sealing agent ($2)
  • A 2x2 inch square of non-conductive, impermeable, heat-resistant material (optional but recommended). I used rubber cut from an old bicycle tube.
  • Cleaning supplies:
    • An old toothbrush
    • Cotton swabs
    • Compressed air is helpful

You may also need:

  • A multimeter or continuity tester (this is helpful in determining if the fuse is blown).
  • A 4.5 inch length of rubber or plastic tubing, with an outside diameter of 3/4 inch or 13/16 inch. This is only necessary if you are removing the heating element. ($1.50)
  • Some extra insulated, stranded, flexible electrical wire (for positioning the fuse holder as desired).
<p>Hi, i have 2 boneco 7142(used to be air o swiss) humidifiers.both stopped misting. There is no brown fuse on mine just a wire(see pic) and there is continuity in that wire. Any ideas?</p><p>cheers</p>
<p>Wow who would have thought that a pneumatic vibrator would make such a difference! I find that in life there are often things wrong and it takes such an easy solution to fix it! Sometimes we over complicate or make things really dramatic.</p>
<p>My AOS 7145 humidifier only produces mist if it's tipped sharply to the left side - 20-30 degree tip. If it's on a flat surface, the red light comes on even when the tank is full, and there's no mist. Any idea what problem could cause that? I'd really like to fix it. Thanks.</p>
<p>I opened it up. It was filthy. And it's pretty clear what part is causing the problem. How in the world did the ultrasonic vibrator unit get so rusted and corroded? I see it's also cracked. I'll try to clean off the corrosion and repair the crack, but it appears beyond repair. I wonder if they sell this part.<br><br>Thanks very much for this Instructable post. I don't know why it never occurred to me to open up the humidifier to look inside. Duh!</p>
<p>Well, it was easy to separate the electronics from the casing, so I can aggressively clean the casing. There is a little bit of corrosion on the board, but I'll be able to clean that up with some 99% isopropyl alcohol and a chamois swab. </p><p>The corroded casing is a bigger problem. I might be able to remove the rust with a vinegar soak - works with cast iron. I have some silicone I can use to seal the cracks. I guess that's what is causing the leaks and the corrosion. Fatal flaw in this humidifier, apparently - seems to happen a lot.</p>
<p>this is great! i went through mine and all i could find was no <br>continuity across the terminals of the vibrator itself. i would think <br>that there should be. could this be my problem or is back on the board <br>somewhere? the fuse tests good.</p>
<p>My fuse is good on mine. I went ahead and replaced it but ultrasonic vibrator still does not work. Any ideas? Everything else works fine. I don't see any blown resistors or diodes either. </p>
<p>Nothing seems gone or broken on mine either. I even had Amazon send me a used one to yank parts:) And still, it doesn't work. Although the used one they sent had gone through a serious meltdown in the power area. It was deformed, Amazon Warehouse deals, they will sell anything, lol, thing was toast on inside:)</p>
I ended up replacing the whole card that has the ultrasonic vibrator and that fixed it.
<p>What type and size of Torx bit did you use to open the case? I have a <br>small 12 pc &quot;star&quot; set, and none will work. Thanks for the instructable.</p>
<p>You need the type of torx set with the security hole, a #T20 is what I used. Bought a whole security set by DeWalt for $17 at Amazon. I went through all of this, fuse had continuity, and it still won't produce mist. I really need to find a new ultrasonic unit, they are on internet, #6046FH3937A, but in a language that I have no clue what it is, or if I can buy the part. Any help any one? </p>
<p>you need the security type,while hole in the center...can find at ace..harbor freight...but honestly, i just used a small blade micro screwdriver and fit in between the center and unscrewed...easy...</p>
<p>wow!..great instructions. wish the whole internet was like this!</p>
<p>Such a good entree into the guts of this. Thanks for your careful work and presentation. What would you suspect/ do if the u'sonic vibrator produces vapor but won't propel mist into the room? I've had this apart and it looks new and clean inside. I'll try decalcing again -longer this time and see what that does.</p>
<p>I ,too, suddenly have no mist. Model 7135 is 4 years old (date stamp inside is Sept 2012) and we have used for about that long.Suddenly noticed that I can feel air coming out of the spout, the controls work (can heat the air) but very faint. No mist. The humidified formerly produced mist that soaked anything too close.</p><p>I keep clean with EZCal and I have a separate small silver thing in the water reservoir to also prevent bacteria from growing. No build up, no gunk anywhere</p><p> Water in the water tank vibrating when the device is turned on but not moving.Water seems to flow through the filter, I hear the glug slug when I fill. Taking water tank off base I see water in the base</p><p>Opened the bottom and amazingly clean, no cracked anything , the flywheel inside turns (someone elsewhere has posted he had white gunk blocking the flywheel).parts are clean.</p><p>I brushed off and closed</p><p>Am replacing the filter granules. That is the only thing I can think of but cannot understand how a used filter would block mist. </p><p>May have to purchase new, I fear, if fresh filter granules are not the answer</p>
<p>This is a great article! However, my issue is the display is giving me a consistent reading of 80% humidity when this is obviously way too high. I think that the hygrostat is compromised in some way and giving bad readings? I'm thinking of opening up the bottom (as in the article) and looking at the humidity sensor board? I have had the unit for a number of years and it has been siting (with water in it) for a while, so perhaps there has been a leak? </p>
Any luck with your hygrostat fix? I have the same issue
<p>Thanks this worked out really well for me. My base was cracked. It leaked on the circuit board and my fuse was blown. Pretty quick and easy fix!</p>
<p>Wow that's an awesome fix, and probably saves a whole ton of money! Thanks for sharing!</p>

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