Thread: Compressor build

I just built one. I'll try and post a pic and step by step.

Here's a somewhat of a step by step. I'll try and make it as clear as possible.
buy a small compressor used or new (I bought a 3 gal for $40 on craigslist)
take off the cover and motor. note where the hot wire(black) goes, neutral(white) and green(ground) go and mark with a sharpie or make a sketch.
determine which wires on the refrig motor are hot and neutral. I did this before taking all the fans, thermostat, etc off the motor. I also used a multimeter to confirm this. I can give specifics on checking this for the electrically challenged.
I kept the metal tray the comp is mounted on and used that for my build. its better than the plastic POS that you get with the tank.
drill holes where necessary in the metal plate so you can mount it to the tank. use the same screws that held the plastic one in place.
Starting from the outlet cord: black wire(hot) to on/off switch, red wire from on/off switch to pressure switch, black wire w/white stripe to compressor. White(neutral) from outlet cord directly to compressor.
I put a filter between the comp and tank because there seemed to be either moisture, oil or freon coming out of the comp. when I ran it a bit. I use the 1/4" copper tubing already attached to the comp. w/ a compression fitting to attach the filter. I also used the rubber hose w/ a hose barb fitting to run from the filter to the tank. I used the existing check valve which is 1/8"npt. You may need an adapter fitting depending on how you attach the hose. You'll also notice in my pic, I used part of the original plastic cover. The on/off switch is made to clip in this cover, so I cut the plastic cover to fit the area between the comp. and gages w/ a jig saw and attached it with one of the screws in the existing screw holes. I added that red shut off valve which is a 3/8" gas ball valve w/ adapters to reduce it to 1/4" so I can shut off the air without turning down the regulator. If any of this is not clear, let me know, I'll try and explain further.
Using an existing compressor to Mcgyver this thing was much easier for me because you avoid all the welding and most of the parts you need are already there.

that's a great job mate, and a good walk through too

A couple of questions.
How does the compressor keep from overheating? its usually the gas that helps cool it.

How does it stay lubricated? the oil is usually in the refridgerant.

Im just wondering how this would hold up under long sessions.

Since I just built this thing, I'm not sure how it will hold up over the long run. I will try and replace the volume of oil that I catch in the filter with new silent air oil. With the 3 gal tank, I'm hoping it won't have to cycle too often and won't get too hot. After I use it a while, I'll let you know how its holding up. If it doesn't last, I'll just get another refrig compressor from the scrap yard and start over.

I've been using this compressor since June and its still going strong and no problems what so ever. There isn't anything I would have done differently since its running great for 5 months now. I got the compressor from a scrap yard and he just gave it to me at no charge. The scrap guy mentioned that some of the local appliance stores bring in old refrigerators a couple of times a week, so I was thinking to also ask them if they would sell or donate an old compressor motor. Another way to find them is to drive around the night before people put out large trash items. In my neighborhood, the garbage men will only take oversize items like refrigerators one day per week. You can also try Craigs List. If you find an old compressor motor, make sure you test it before you start building this thing because sometimes the reason the refrigerator is being tossed is that the compressor stopped working. If you have any other questions, let me know.

I built one way back in 2004, the how to is up in the member articles section of the web site. Mine still works fine and it has been used a lot in that time. As long as you watch the oil levels in the compressor it should last.

don't worry about how hot it gets some compressors will get as hot as 500 degrees. the one I built hardly gets warm

Originally Posted by HerpHandler

A couple of questions.
How does the compressor keep from overheating? its usually the gas that helps cool it.

How does it stay lubricated? the oil is usually in the refridgerant.

Im just wondering how this would hold up under long sessions.

I ran a test on a fridge compressor as a vacuum pump by blocking up the intake, i ran it for 1 hour and it did get quite warm but not overheating.
The oil is located in the bottom of the compressor and is drawn up a spiral tube that is attached to the motor shaft, as the motor spins the spiral inside the motor shaft draws the oil up the shaft to the top to lubricate the big end bearing and piston wall, i think gravity ensures the oil stays in the chamber rather than working its way around the fridge tubing. you can put a oil catchment similar to a moisture trap on the compressor outlet pipe to catch any stray oil, check the manufactures site and determine how much oil you should run in the compressor then drain the old oil out and refill with the correct amount and you will be fine.
theres a guy on youtube user name aussie50 check him out hes got some great compressor knowledge

Putting a fan on your compressor setup would probably help keep it cool, the more you keep the compressor from super-heating, the longer the oil and inturn the compressor will last you. The fan would also help you keep the overspray and dust away from the compressor. That would help you keep your intake air a bit cleaner too.