+ 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
First of all you have to make sure the compressor on the fridge was ok. Quite a lot of fridges are thrown out eventhough the compressor is perfectly ok. 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 electricaly 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.