A few months ago I decided I wanted on-board air for my pickup. After a bunch of research I decided against an electric compressor and to convert the A/C compressor I had to an air pump. Most of the information I found on how to do this was scattered widely all over the internet, so I thought I would collect it all in one place. Here are some key points:
-- Compressed air stores lots of energy, and accidents can turn ugly. Make sure the components you use are up to the pressure you will be applying, plus a nice fat safety factor.
-- Unless you luck into a York compressor, A/C compressors need oil. This is well known, but bears repeating.
-- The input and output on the Toyota A/C compressor are standard flare fittings. At least they were on this one, 5/8 on the input and 1/2 on the output I believe.
-- If you just want to air up tires, you don't need a tank. I want to run air tools as well, so I added a five gallon tank.
-- If you are lucky, you can get most of what you need at your local scrap yard.
Stick around to the end for a souper duper air filter!
First we mount the AC compressor on the engine. Mine came with a mounting bracket, and I used some very temporary spacers to get the pulley lined up.
![](https://imgur.com/g4DgiWp)
Getting the right oiler was a bit of a challenge since the input to this compressor is a pretty low-flow system. I finally settled on the Arrow Pneumatics L354W because it is designed for such systems. Here it is on the compressor with a filter to catch incoming grit:
![](https://i.imgur.com/3uC3xin.jpg)
I ran the output past the front frame member and above the skid plate to the opposite fender well where a water/oil separator and the pressure switch were mounted. The union is necessary to give the tubing freedom to get around all the corners involved. (skid plate removed for clarity)
![](https://i.imgur.com/UQvuf4W.jpg)
This is the separator (Arrow Pneumatics F554W) and a Square D Pumptrol pressure switch. The switch is adjustable from 100-200 PSI shutoff. The safety valve is set at 200 PSI.
![](https://i.imgur.com/6GZ00G0.jpg)
I ran soft copper tubing throughout the whole system. I got it as scrap at my scrap yard so it was cheaper than new hose, plus it may hold up better. This runs along the driver's side frame to a tee. From there one branch goes to the pressure regulator and output, and the other to an air tank on the driver's side at the back.
Here's the air tank:
![](https://i.imgur.com/hTonmpU.jpg)
And the box to house the regulator and output:
![](https://i.imgur.com/yZX0fOK.jpg)
![](https://i.imgur.com/4EBqku1.jpg)
I know, there are holes in the front of the box. Those will be covered up soon.
I debated about what to do for an air filter. Most air filters I could find cost $$$ and open air filters are known to get dirty faster than I like. So I decided to make a souper duper soup can air filter. I drilled a hole in the bottom of a soup can and soldered a pipe into it, protruding into the bottom of the can about an inch or less. Then I stuffed oily rags made of tightly woven cloth into the can and made a bracket to hold them.
![](https://i.imgur.com/iZwtYef.jpg)
I'm going to do some formal tests on the soup can filter soon. If it passes it gets to stay, otherwise it will be swapped out for something more conventional.