I've been wanting to mount my compressor somewhere for ages. I finally got around to it.
Having stopped carrying water under the van (I didn't like the water tanks I'd made) I thought I'd utilise the tray I'd made. Plenty of room on it, so I relocated the auxillary battery there too - it was previously inside the back of the car (and vented) but under the car will be safer.
Collect the bits. I have the tray already from a previous water tank project. It mounts solidly under the back of the van between the LPG tank and the rear of the vehicle. Its made from 2mm thick Gal Angle, and Gal sheet. Its higher than the LPG tank so doesn't create any clearance problems.
The air fittings required came to about $38.00. That includes a T piece, two nozzles, two outlets (closed unless something's connected to them), 5M of hose, and 4 stanless hose clamps.
Modify the compressor. I stripped it down and cleaned it out (there was lots of sand). I turned the head around 180'" so I could have the inlet where the outlet was. That relocated the valves. The piston has an indent in it to allow for the rivets on one of the valves. To allow for this I drilled 2 small indents on the other side of the piston face. Fit the T-piece to one side (using plumbers tape) and re-fit the heads. I ran the intake pipe through the handle and used some cable ties to secure it. Nothing's likely to be pulling on it so thats probably not required.
Mount the compressor. For that I used 4 bolts with nylocks nuts on them. This allowed me to only have the bolts done up enough to stop the compressor from departing. Between the compressor and the base are slabs of foam (lagging actually). The bolts go through them. This will allow the compressor to move when being used so it won't shake itself apart. If you still have the wobble base on yours you can just bolt that down - mine broke ages ago.
Mount the battery. I made a surround for the battery to sit in out of thing angle. Then cut two lengths of 10mm threaded rod and welded them all to the bottom of the tray. Using a bit of plastic for isolation, a strip of metal across the top with a couple of nylocks holds the battery firmly into the tray.
Install under the van. With help from a mate we bolted it up under the van and routed the air hoses to each side of the van. Routed all the cables and air intake through grommits into the back of the van.
Wiring. Now forgive the dodgy wiring but there's a heck of a lot going on in the back of this van :-)
The solar regulator is for the 4 solar panels in the Crystalite Roof. It has a low voltage regulated output that cuts out at 10.8v. Maximum 10A. I've got that wired through to a fuse box which has all the front electronics (computer, usb, accessory plugs, gps, and stereo), and both sets of rear accessory plugs.
The battery output of the solar regulator joins to the accessory side of the Dual battery regulator (another low voltage cutout/relay of sorts - cuts out the starting battery when it falls below 12.7v and cuts it back in so the alternator charges the auxillary battery when the starting battery reaches 13.8v). The auxillary battery connects to that dual battery regulator of course so the solar gets to it through that. The inverter connects directly to the auxillary battery there. The compressor and rear spotlight (wired to come on when in reverse) are then connected through separate fuses and relays to the main battery (again through the dual battery regulator).
Yes its a mess. But it all works. I can see the state of the battery easily. I can run any accessory or the fridge with impunity knowing I won't damage the auxillary battery by discharging it too much.
Oh yeah, almost forgot. The switch for the air compressor! Mounted it in the drivers sidestep footwell. That way I don't need to climb back into the van to turn it off and on. Just connect the hose to either side, and turn it on. Have to remember to turn it off when swapping sides.
While I was out there I also put a new sticker on the windshield and used a strip of window tint to cover the top 8%of the windshield (great for afternoon sun).