Here is my how to on modifying fridge compressors into silent air compressors. They are ideal if you need:
+ a silent compressor
+ a high pressure compressor
+ have little space and/or don't need a typical shop compressor

Typical fridge compressors are 100 - 300 watt units, deliver 0.7 - 1 CFM of air and can reach pressures over 500 psi.

Here is a video where I discuss the process briefly (I'll make a new one soon - feel free to comment or ask questions)


There are two ways to get a fridge compressor you want to turn into an air compressor:
A) buy a salvaged compressor
B) salvage one yourself from an old fridge

In case you choose option B then you have to remove the compressor from the fridge yourself - that process is described in the next step. If you already have a salvaged compressor then go to step 2.

Step 1: How to remove the compressor from a fridge

Quite a lot of fridges are thrown out even though the compressor is perfectly ok. You can test it by plugging it in and the compressor should start. If that's the case you can proceed to wire, as shown here (requires an on/off switch all the other parts are already there)

In some cases the compressor is working, but its starting circuitry is broken - and the owner didn't knew it. I have experienced this on two occasions so it is not rare at all. You can test the compressor electrically using an ohm meter

Here is my video on how to perform this:


The pic below shows where to cut the copper tubes. You should always salvage as much of tubing as you can. It doesn't really matter what tool you use just make sure not to crimp the tubes - nice square cuts are preffered. 

Don't forget to salvage the mains cable with the plug. Most fridges have a sort of junction box right on the side of the compressor as well as starting relay/PTC relay (all of it is house in a rectangular plastic enclosures you find on the side of the compressor). There will be a wire running from the fridge compressor to the inside of the fridge - it goes to the thermostat and powers the light inside the fridge - again the longer the lenght that you salvage the better.
It's important to note that if you cut the tubes you release the refrigerant. Old refrigerant is bad for the ozone layer...new refrigerants are not as bad for the ozone layer but they still are thousands of time worse for global warming than CO2. So to do this responsibly, you have to either get a fridge that has already had the refrigerant removed, or you have to find a refrigeration technician who can do that for you. <br> <br>Very cool to make good use of scrap--sorry to have to inject this note of caution.
Yes, you are right. But freon hasn't been used for about 20 yrs so vast majority of fridges you will find won't have it. What's more, if you leave an old fridge with freon it will leak out the refrigerant anyway.
It is for y author<br>I removed compressor from my old fridge .that time it was working <br>But after words i droped by mistake <br>It was tilted up side down <br>Then after it is not working <br>I tried a lot but it is not workingat al lhelp me out of this!!!.<br>Plz......
That's right--classic freon (CFC), which had the worst ozone layer effect, was phased out in 1995. If you find a 20-year-old or older junk fridge, that's what's in it. The main replacement used since then is HCFC. That has something like 10% of the effect on the ozone layer--not nearly as bad but still pretty bad. And there are HFC refrigerants now that have no effect on the ozone layer.<br> <br> However, all three--HFC, HCFC and CFC--are bad for global warming--thousands of times worse than CO2! So even if you do this with a fridge made in the last few years, it's a serious problem. In most places, there are programs to make sure fridges are safely taken care of, with the refrigerant collected. They'll pick up old ones for free, or even pay you for them. You can check in your area, or find many of the programs by zip-code here:<br> <br> <a href="http://www.jacoinc.net/recycleNow.aspx" rel="nofollow">http://www.jacoinc.net/recycleNow.aspx</a><br>
I removed compressor from my old fridge .that time it was working <br>But after words i droped by mistake <br>It was tilted up side down <br>Then after it is not working <br>I tried a lot but it is not workingat al lhelp me out of this!!!.<br>Plz......<br>
<p>Oh wow, how interesting to know that you can modify a fridge compressor into an air compressor. The one in the picture sure reminds about seeing one at a certain compressor service company store. It's actually something that I'm looking for at the moment in order to clean the air ducts.http://www.compressedair-systems.com/services.html</p>
<p>Waste removal centers and recycling centers have special tools that remove old refrigerant - essentially a needle and hose hooked to vice-grips to capture the gasses. They crimp them directly to the copper tubing. They would probably do this for free or very cheap if you ask around. </p>
This is a diagram of a NLY7F compressor. I'm having trouble figuring out which wire to connect to what. Can ye help me out? Thanks a mill. :)
<p>Thanks for sharing these great guidelines. Everyone can go through http://aircompressorjournal.com/ to learn more about air compressor. Many thanks. Hope to see more tips in the future.</p>
<p>I am a licensed refrigeration technician and I notice that you fail to <br>mention that this is both ILLEGAL and DANGEROUS. Pressures inside that <br>system when the unit isn't operating can reach well over 100PSI and when <br> you cut any of those lines that refrigerant will flash off into a gas <br>and this will cause an extreme temperature drop and the result will be <br>instant frost bite if it contacts your skin. You cannot, by law, <br>intentionally vent any refrigerant into the atmosphere. You state here <br>and other places that the &quot;freon&quot; used today isn't as bad for the <br>environment and that is wrong on every level imaginable. Refrigerants <br>used in low temp equipment are going to be either R22, R134a and in <br>some cases R404A. These are NOT environmentally safe substances and <br>therefore are regulated by the EPA. In fact R22 has been phased out <br>because of this. Venting carries a hefty fine and rest assured this will <br> be reported accordingly.<br>Furthermore, using a refrigeration <br>compressor as an air compressor isn't very wise. The unit uses the <br>actual refrigerant, that you illegally removed, to cool the internals. <br>The oil that is inside the system is considered hazardous waste.</p>
get off your high horse dude! narc!
Go ahead, cut one open. Make sure you put your face directly over the line when you do. Or maybe you go fuck yourself....either way.
<p>Actually, R134/a (is BORDERLINE Environmentally safe, as most 'Air Duster', Sports Horn, and Even most aerosol products are pressurised with it.. But I well understand your concern, having been a Firefighter/Haz-Mat-II warm-zone first responder. </p><p> To the author, I also would HIGHLY suggest bringing a salvage refrigerator to a HVAC contractor, to have the refrigerant safely extracted. (vacuum pump system) (since it could be R12, which is still illegal to vent.) and leaving the system sealed at least 20 minutes before allowing venting to the atmospheric level. I haven't read further into the instructable, But also drain as much of the refrigerant oil as possible, and replace it with air-compressor oil, which will not foam, and cannot be contaminated like the refrigerant oil does. (But NEVER more than the amount you drain! as this will get oil into the output air.)</p><p>One note to HVACPro, Not entirely unwise, as most compressors are essentially the same inside, as air-cooled, and using the Air Compressor oil will also provide cooling, carrying the heat to the metal case.. The thickness of the case is usually adequate incase of seizing/exploding. (as long as the case remains welded!) I've seen plenty of videos of converted compressors, and 'Exploratory Autopsies' of failed compressors to know the case is there for a reason. (especially one of a dual-compressor outdoor system, where the crank arms on a 6-cyl. Compressor failed, and shattered inside. Resulting, eventually burned-out the 2nd compressor's windings)</p>
<p>that diagram showing what appears to be an outlet trap seems backward would it not be better to reverse the flow?as you currently have it, once the condensate/oil reaches the outlet tube, it will act as a siphon. </p>
<p>I am using this to build a high pressure bottle burster.</p>
<p>I am using this to build a high pressure bottle burster.</p>
Very useful instructable. I am using one of these compressors since maybe 30 years. It has very high compression but very low flow. I use it only to inflate my bicycle wheels. I tried to use it to paint, but because of its low flow it did not worked.
<p>You could run it through a pressure switch to an air tank. The pressure swithc will shut off the compressor when pressure in the tank reaches a preset pressure, then will turn back on when pressure drops below another preset. </p>
<p>Thanks, antonc81.</p>
You can also use air conditioning compressors - they offer a lot higher flow. <br>
Thanks for the info, I didn't know that.
guys, if you do want to use refrigerant compressors, please contact your local HVAC technician about recovering the refrigerant inside. The ones that are extremely harmful are R-12, and R22. There are plenty more but in residential applications, these are it. R-134a is considered an HFC which doesn't have chlorine, so it has a 0% ozone depletion. But it's a greenhouse gas. For those wondering, 1 chlorine molecule can destroy 100,000 ozone molecules. So at least contact someone to recover these units.
hi, can i use a air conditioner compressor ? thank you!
Yes, of course you can. They are even more practical for everyday use than fridge compressors, because their CFM/minute is higher. I haven't ever built one because they are hard to get where I live but everything is pretty much the same. Here's one thread found on them - http://www.spudfiles.com/forums/i-have-an-a-c-compressor-to-convert-questions-t18828.html <br> <br>There are like tons more examples there but be warned that the search function really sucks ;-)
Very clever use of more &quot;throw away&quot; stuff in our disposable society.

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