Introduction: Super Silent Compressor Built Out of an Old Fridge/Water Cooler

When you're working indoors, an ordinary compressor can be pretty loud and distracting. The only other option is to invest in a silent compressor which can, easily, cost 3-4 times as much. More than that, unless you're ready to spend an obscene amount, they are rarely able to put out the same psi as a standard compressor.

To the do-it-yourself type, this isn't a problem. Using a standard fridge/water cooler compressor, an old pancake air compressor, and a bit of soldering skill, you can build your own SUPER silent compressor that is barely audible when running, and is capable of putting out, up to 120 psi safely. It operates a bit more slowly than it's mechanical counterpart, but not by much. This model can pressure up in under 4 minutes.

This project should take you, no more, than an hour to build in it's simplest form, however there's plenty of room to improve the design. Simple upgrades such as a custom mount for the fridge comp, a wire box to clean up the harness, etc. will go a long way to making your build prettier, but aren't necessary to it's function. There is almost zero vibration and as much noise as your refrigerator has when it's running.

Step 1: Tools and Equipment

Equipment:

pancake compressor with separate pressure switch
fridge or water cooler compressor, (either will work fine. The one in this instructable is from a water cooler)
1/4" copper line
compression fittings
various wire connectors/marettes
tie wraps

Important note: When locating your fridge/cooler compressor, it's a good idea to have it drained by a professional. Simply cutting the tubes and letting the gasses out is just plain bad for the environment, and a hazard to you if inhaled directly. If having it drained isn't an option, locate a unit that has been sent for recycling. More often than not they end up there simply because they've leaked all of their coolant and no longer provide refridgeration, however the compressor itself should still be operational. Nevertheless, you should still take precautions, when cutting the lines, by using a ventilator.

Tools:

Soldering torch w/ solder and flux paste
teflon tape
monkey wrenchs
drivers
wire stripper/cutter

Step 2: Identifying the Tubes/electrical on the Fridge Compressor

Electrical:

On the side of the unit, you'll find the thermal overload/power connection. In the second picture you can see the connections. You should make note of how it's connected when you remove it from the fridge/cooler and wire using the same colors, with the ground wire connected to the body of the unit itself. There is a thermal overload built into every unit that protects it. One flaw with a fridge compressor is that if you shut it off, then turn it on right away, the thermal overload will kick in. Don't worry if this happens. Just wait a few seconds and try again. The thermal overload should reset itself. It'll also protect the unit from power spikes, in case you fudge the wiring like I did on the first unit I built.

Identifying The Tubes:

More often than not you'll find three 1/4" tubes exiting the unit with one by itself on one side and the other two side by side on the other. An easy way to figure out what is what is to connect the comp to power then feel the end of each line for suction or discharge. On 'most' models, the suction tube is the one that's by itself, and the discharge tube is the lower of the two on the opposite side. The third tube is unused. It's called the process tube, and is generally only used at the factory for testing. This tube should be crimped and/or soldered closed.

Step 3: Important Choices on What Type of Air Compressor to Canibalize

The choice of air compressor you plan to use for this project is extremely important. I've built a few of these, for other people, and have found that the pancake models with the separate pressure switch tend to work the best. The larger models that incorporate the pressure switch into the power  have a unique issue. There is usually a bleed valve, incorporated into these, that release the pressure going from the compressor to the tank. Unfortunately, this switch needs a strong pulse of air to activate, that the fridge compressor just can't provide, so it will leak incessantly, causing your tank to fill more slowly. You can disable the switch, however it's part of the pressure regulator in the unit, so you will also be disabling your compressor's ability to shut off when it's full, making it unsafe, or in the very least, annoying since you'll end up having to keep a constant eye on it.

Suffice it to say, having an air compressor with a separate pressure switch will make the job a whole lot easier.

Step 4: Installing the Fridge/cooler Compressor

Attaching the Fridge Comp. to the Tank:

For the sake of cost and simplicity, I simply zip tied the unit onto the tank. There is virtually no vibration and no worry about it working itself loose over time. You can choose to create a mounting bracket, for cosmetic reasons, however, if you're like me, it doesn't have to be pretty. It just has to work.

Soldering and shaping the Line:

You may need to solder new line and add fittings to make your connection, however more often than not, you can just recycle what came with the air comp, and the fridge. The line you see in the pic was existing from the air comp and was 1/4" I.D. (internal diameter). The line exiting the comp was 1/4" O.D. (outer diameter, so it was simply a matter of a bit of sanding to make the connection. The rest is simply soldering pipe together much as you would if you were working with plumbing. Just lay some flux paste in the joint, apply heat from the torch then let the solder fill the gap, and presto...you have a connection. You may need to make some dramatic curves in your line in order to get it to line up with the intake on the tank. I like to keep a piece of flexi-shaft from an old weed trimmer on hand for just such issues. You can feed it through the pipe, bend to the desired shape and then draw it out again. It's a great way to prevent kinks in the line that could otherwise interrupt the air flow.

Fixing Leaks:

I can't express, enough, how important it is to make sure you don't have any leaks. This is where the teflon tape comes in. Fridge comps. don't put out a lot of volume, so any leak, no matter how small can seriously impede it's fill time. Simply put, check every connection, and tape everything.

Step 5: Wiring the Power and Pressure Switch

This is just a simple diagram I made up for a friend that wanted to build his own unit. Should make the set up easier.

Step 6: Finished

You're done. Everything else on the unit should stay the same and you can connect up to it as you normally would if it had a conventional compressor attached.



Hope you enjoyed the instructable.

Comments

author
AnthonyR141 made it!(author)2016-08-27

What if I do not have any if the wiring. .can I wire directly to old compressor and use that relay

author
jonestation made it!(author)2015-06-22

hi, may i know if it is possible for a 1/5 hp fridge compressor to fill up 30 Liter tank, or 50 Liter tank up to 115psi ? Will the compressor burn out for running too long?

author
antagonizer made it!(author)2015-06-22

A fridge compressor will work with a 50L tank but the fill is pretty slow. Fridge compressors are designed to work for long periods and can attain pressures as high as 250psi.

You should beware of some large tanks as their pressure switch is part of the on/off assembly which won't work for you. It should be mounted directly to the tank as you see in the pic "Installing the fridge/cooler compressor", otherwise you'll be manually shutting it off when it reaches pressure which can be dangerous.

author
jonestation made it!(author)2015-06-26

Thanks for reminding. Is there a specific name for that type of pressure switch? Most of the compressor tank i saw here are using typical black box with either a red button on top or a pin on the right of the pressure switch box. Can i change the pressure switch to the type you recommend?

author
antagonizer made it!(author)2015-06-26

You would have to find one that fits inline with the tanks air inlet. I haven't seen one in stores anywhere but it doesn't mean they exist. It's basically a switch that's wired inline with the input voltage. When the tank reaches a designated pressure, it cuts off power to the pump.

author
vectorization made it!(author)2015-06-17

I'm using a NLY7F compressor. Though I'm having trouble figuring out which wire should I connect to a switch. Could you help me out? Thanks :)

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author
antagonizer made it!(author)2015-06-22

I'm not familiar with your model of compressor, but your switches should be on the hot (black) side and the neutral (white) should be wired directly. Looks like that's position 'e' on your diagram. Everything else is redundant and are just line out for things like the fan and light. You can terminate those and marette them. The green wire should be grounded directly to the chassis or tank. Sometimes a compressor will use another color for neutral, like red, but black generally is always black.

author
Msinks made it!(author)2015-03-26

Am planning on using this compressor on a small packaging machine as a school project to extend and retract about four cylinders in a certain sequence...
What effect on the compressor will this have over time, since its been modified to work has an air compressor? Will it shorten its life span?

author
mark.andersen.1293 made it!(author)2014-10-08

I repurposed the compressor from a badly damaged fridge many years ago to run my air brushes I used to paint my models, but I never thought about hooking it up to a tank. Great Idea. :-)

author
lov2teach made it!(author)2014-09-14

I'm passing this instructable to my husband. It's a bit beyond my skill but am sure he can make this.

Thank you so much for giving of your time to make this instructable as well as the video!

author
geoalcai17 made it!(author)2014-06-29

using water tanks instead of pancake comp. is it possible?

author
antagonizer made it!(author)2014-06-30

Depends on their working pressure. It should exceed what you expect to pump your tanks to by at least +50% If you're not installing a pressure cut off switch, I wouldn't recommend it tho.

author
FN64 made it!(author)2013-12-18

Now that's pretty innovative! Could one of these fill a larger tank?? I realize it would take more time to fill but would it run for the required time without over heating?
I have a 10 gallon compressor that's noisy as heck for running an air nailer (brads) This mod would be most welcomed if it's do-able.
Great 'ible..clear & easy to understand
Thanks..FN

author
antagonizer made it!(author)2013-12-18

I've build one using a 10 gallon tank, and wasn't impressed at the fill time. Takes about 15 minutes to compress to 100psi. If you're willing to suffer the wait, then it'll do the job for you.

author
tcsinstructables made it!(author)2014-01-21

Ive seen a larger tank on youtube that uses 2 fridge compressors,, Im thinking on trying this myself, but for now, I am intersted in trying to make one, and ensure that it runs at least 45 psi, which shouldnt be a problem,,,, my issue is, I dont know anything about compressor,,, I have one in my garage that I think has a leak in the tank, not sure,, and dont know how to find the leak if it does,,, now,, I need at least 1.2 cfm at 45 psi to run my high speed etching machine,,, how would I tell what cfm its running? after my first attemp at this, with a single compressor, I will try the double compressor....

author
sparhawk7 made it!(author)2014-06-18

take a sponge and soapy water. apply liberally. look for bubbles. idk how to fix the leak itself though. sorry.

author
zappenfusen made it!(author)2013-12-31

What exactly is inside the sealed compressor case? A compressor, right? I've often wondered how the refrigerant compressors worked but have yet to take a sawzall to one. Neat idea and one I'll try as I've a wealth of old r.t.u. compressors that lost pressure years ago pre freon ban. The cheap pancake I use now I put in the yard and run a line into the garage due to the 110 db. noise.

author
antagonizer made it!(author)2013-12-31

Basically yes, and a lot of oil as well that it uses to muffle the sound. I got curious once too.

author
DavidFerAndersson made it!(author)2014-03-05

Hi, thank you for a good 'ible!

I've been looking to do this for my airbrush setup since the tiny piston compressor Im using it making enough noise to resonate to the downstairs neighbours..
But, I've read elsewere that these compressors let the oil travel through the lines, is this an issue you've noticed? If this is the case, I guess it would dry eventually..

Thanks again!

author
antagonizer made it!(author)2014-03-05

I wouldn't worry. I've never had that happen and I've built 6. Btw, oil is good for air tools, tho for an airbrush, you should use a moisture trap regardless. That way, if it did happen, you wouldn't even notice.

author
DavidFerAndersson made it!(author)2014-03-06

Cool, thanks!
How often do you need to refill the oil in the compressors?

Im using a tiny moisture trap close to the gun at the moment, but I need to get a new manometer, so Im probably gonna get a combined separator / manometer.

author
antagonizer made it!(author)2014-03-06

Never. The oil in the compressor is, essentially, there to baffle sound, and tho it does act as part of it's operation, it doesn't use any of it up. As long as you didn't spill any during the build by flipping it upside down, you won't need to top it up, which you can do with some 10w30, btw. The more moisture separation, the better. I'd recommend getting a filter/regulator with a built in water trap on the tank end, and an inline hose moisture trap. Both can be acquired from airbrush shops. Water in your lines is the biggest enemy with the air eraser.

author
DavidFerAndersson made it!(author)2014-03-07

Thank you for your exellent replies!
Im just getting started with airbrushing, so theres quite a bit to figure out.
Thanks again!

author
antagonizer made it!(author)2014-03-07

Just remember, if you build one get a tank that has the pressure switch in the tank, like most pancake tanks have. If you see a switch like this one, it won't regulate properly for you.

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author
kevohill made it!(author)2014-01-25

I've been looking into upgrading my pancake for a while, but I'm not sure WHOM I should talk to in order to get a fridge drained. My recycling center has plenty of ACs and fridges, but I haven't taken any since I've had no luck finding "professionals" on Google. I imagine I'm just not searching for the right things. Can anyone help guide my search? (I'm located in Massachusetts, USA)

author
antagonizer made it!(author)2014-01-25

You can try appliance repair companies. They should have the equipment to drain, and recycle the gas. If you find one of the small water coolers, they have a great little condenser in them for this project. That way you don't have to cart away a heavy fridge or ac unit.

author
zappenfusen made it!(author)2013-12-31

Would the use of the compressor from a 3 ton roof top unit cause any specific problems as compared to a refrigerator compressor?

author
antagonizer made it!(author)2013-12-31

If it runs off of 110 and you can pipe it in, I don't see why not. Pressure is regulated through the switch, so there's no risk of over overloading the tank. With that criteria any refrigerant compressor would work.

author
stechi made it!(author)2013-12-17

Very interesting ible.
From the video I gather you re planning to use this to supply air for an air brush. I t might be good to say that in the instructions, in case anyone thinks they can use this for their scuba diving tanks or something.
What happened to the refrigerant? Old fridges contain nasty Freon that is illegal to discharge and newer ones contain methane etc, which is a bit explosive, you might want to warn people about that.

author
antagonizer made it!(author)2013-12-17

Scuba, btw requires upwards of 3000psi to fill, and any fridge/standard compressor is unlikely to exceed 130-140 so no worries. Also, a scuba compressor pumps 'food grade' air which is different that what comes out of a standard compressor. Folks with a diving permit would likely be aware of that.

author
antagonizer made it!(author)2013-12-17

Great point. I'm not big on caveats since I figure people will figure those things out by themselves, but in this case it would make sense. I would hope, tho that people would take their old units to the nearest recycling depot to be drained first, and not just start cutting lines haphazardly.

author
boatingman made it!(author)2013-12-17

This is a great idea and I'm going to start on one today. Thank you.

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