Wiring and plumbing an air compressor ?

[VladTepes]

I have an air compressor that I want to permanently mount in the 1995 Defender (say under drivers seat) and I;d like to run an air line to the front and rear of the vehicle as well -so I can just connect the hose as required.

I'd appreciate advice as to
1. How to run cabling / appropriate wiring; and
2. How to plumb the air lines, connectors etc.


I haven't given any thought to tanks or anything - it'll just be for airing my own tyres up and down primarily and I'm never in that much of a hurry that I can't afford a few minutes to do it.

[Blknight.aus]

come and have a look at my disco which is an endless air conversion.. It'll give you an idea...

but I basically gutted a 240v compressor for the control valve then used its ports to direct air front (straight to an under hood fitting) and rear (via a hose under the body and up through a hole in the floor behind the back seats)


were you going to go with an engine driven compressor or a 12V powered job?

[DeanoH]

Err..............................you actually want to increase the cabin noise in your Defender ? :o

I assume you're talking about putting a 12 volt compressor under the drivers seat. I would question the installation of a pressure vessel (air tank) in here though. Visions of catastrophic failure are not pretty. :eek::eek:

Seriously though, if it's for tyre inflation you won't need to run any air lines, just a serious (fused) power cable from under the passenger seat (battery) to a relay connected to the compressor. A thin control wire to a dash mounted switch and a quick connect air line and connector to the seat box side panel (there's plenty of room to mount a female connector/plate here), and jobs right. :)

In the Oka I mounted an ARB twin cylinder compressor (basically under and behind the passenger seat) this way. I also bought an ARB extension air hose, curly hose and inflation tool which fit neatly in a bag behind the seat and can also be used at home off the 'real' compressor if need be. Long enough to reach all wheels on the Oka so no issues with the Defender. (The Oka is the same wheelbase as the 130 Landys, ie. 130").

The only problem with this setup was the crappy relays ARB built into this system, 100 Km down the Anne Beadell and the cheap, crappy Chinese relays had rattled themselves to death. If you have an ARB compressor you will definitely need to replace these relay(s).

As BK points out an engine mounted compressor with an under vehicle tank is a better setup but a heck of a lot more work.

Deano :)

[VladTepes]

Thanks Dave but Deano has it ine one - just a 12V compressor, not an endless air set up which though awesome is not what I NEED. Money better spent elsewhere.

Simple is better so I reckon that's the best way to go. Just wondering what pneumatic connectors etc I need to get....

Oh and I won't be IN the cabin when the compressor is running so all good.....

[n plus one]

Err..............................you actually want to increase the cabin noise in your Defender ? :o

I assume you're talking about putting a 12 volt compressor under the drivers seat. I would question the installation of a pressure vessel (air tank) in here though. Visions of catastrophic failure are not pretty. :eek::eek:

Seriously though, if it's for tyre inflation you won't need to run any air lines, just a serious (fused) power cable from under the passenger seat (battery) to a relay connected to the compressor. A thin control wire to a dash mounted switch and a quick connect air line and connector to the seat box side panel (there's plenty of room to mount a female connector/plate here), and jobs right. :)

In the Oka I mounted an ARB twin cylinder compressor (basically under and behind the passenger seat) this way. I also bought an ARB extension air hose, curly hose and inflation tool which fit neatly in a bag behind the seat and can also be used at home off the 'real' compressor if need be. Long enough to reach all wheels on the Oka so no issues with the Defender. (The Oka is the same wheelbase as the 130 Landys, ie. 130").

The only problem with this setup was the crappy relays ARB built into this system, 100 Km down the Anne Beadell and the cheap, crappy Chinese relays had rattled themselves to death. If you have an ARB compressor you will definitely need to replace these relay(s).

As BK points out an engine mounted compressor with an under vehicle tank is a better setup but a heck of a lot more work.

Deano :)

Hmmm, I just 'upgraded' my (ultra reliable) single engine ARB compressor for the new twin donk model - looks like I'll be swapping out those relays tomorrow.

I ran my old compressor down the side of my drawer system (in a 110) without a tank and used the ARB air hose kit to reach either end of the vehicle. The single motor ARB compressor is extremely reliable as long as you don't cook it - ie stick to the recommended duty cycle.

The new twin donk model is under the rear passenger seat plumbed into the ARB allow tank, mounted under rear seat floor. Can't comment on performance yet but I wanted to improve flow so I could use small air tools if needed. Tank is plumbed using push-fit pneumatic fittings and poly airline.

Both installs used dash mounted switches.

I think the two main factors to a successful electrical compressor install are heavy guage wiring and don't mount em anywhere that gets hot.

[warren9981]

On my Discovery I wired an Anderson plug at the front and the back of the vehicle. The compressor has a plug also. That way you keep the compressor in a bag in the back of the vehicle and just plug it in near where you want to use it.
Simple and cheap, plus you also get 12V power outlets to use for other stuff.

[2stroke]

I fitted the earlier style ARB compressor to the 130 about 9 years ago under the rear seat in the storage box. Initially I brought an airline and fitting out the bottom of the box on each side, a little inboard of the sliders but the fittings would quickly start to seize up with exposure to the elements on a 2 week Moreton trip. What I found best was having them come out just inside the rear doors on the outer panel of the under seat box, well protected and easy access. The supplied ARB inflation hose can reach front and rear tyres and even the ones on the tandem trailer. As for wiring I used most of the hardware from the ARB supplied loom but rearranged it all so that the fuse and relay lived in the battery box, the switch is on the little oval panel below the middle of the dash. I ended up using a pneumatic ram with 2 end caps and the shaft removed as a storage receiver (also in the box with the compressor) as it was free. This setup works for me but isn't the fastest for inflating 4 255s and Dave's a/c compressor would probably do all 4 before mine's done 2. For me though the engine bay is already full.

[POD]

My compressor on the 130 was mounted in the cabin behind the rear seats, but after the rear ARB locker became an oil pump, the smell of 500ml of gear oil washing around inside the cab convinced me to move it. It is now mounted on the LH chassis rail behind the cab. The previous owner had plumbed the vehicle with standard 3/8" flexible air line connected to outlets with jamac couplings that are mounted under the tray on each side just behind the cab, works well as a relatively short air hose reaches the wheels on each side. Would need a longer hose if towing.
All the hose, tees and couplings are easily gettable from an industrial supplier (as i'm sure you're aware), quality female couplings aren't cheap though.

[rar110]

My ARB compressor is mounted on the firewall to the driver/right side of the brake pedal box. I currently need to open the bonnet to fit the hose. I will eventually fit a hose outlet somewhere so I don't need to open the bonnet. The ARB is much faster than my previous truck air compressor. Quite happy with it.

[Drover]

ARB sell full wiring looms for compressors/switches for on and off, lockers etc.
Just need to run the cables.

[VladTepes]

If someone cares to pop up a quick wiring diagram (eg do I need fuses and where) and tell me what relay I need to buy that'd be great.

[Dopey]

If it's any help, here is the wiring diagram to my new compressor that I'll be installing soon. It is for the twin pump compressor from ARB.

[VladTepes]

Thanks - 2 switches? Can you turn each half of the twin compressor on/off seperately?

[Dopey]

Three switches....
Isolation switch for turning the compressor on and off.
And the other two switches for each solenoid on the optional manifold.
As far as I know you cannot run each motor separately utilising the standard wiring supplied ( it does look relatively easy to modify to run each motor separately though).
Something I'm interested in is, is there any advantages or disadvantages to using auto resetting circuit breakers instead of fuses?
Mike.

[Blknight.aus]

they draw some serious amps,

offers on the table for you to come over and I'll crimp up what you need with some NFA cabling, you'll just need to get the grommets and fuses/circuit breakers you want to run (maybe a relay in place of if your going to monitor it and only use it occasionally or depending on the load out of your primary fuse panel I may be able to tap that)

if you buy a recessed nitto or JIC we can also fit that to the seat box so you can have the control switch and air outlet on the seat box (hell buy two have one on each side) and just need a connector hose.

lots of fun options to be played with.

[DeanoH]

The compressor shown in 90@'s picture is what I have. The quality of the wiring loom and switches is quite good but for a simple compressor setup the small high current loom connected to Compressor plug 1 is really all you need plus a single wire from the purple wire in Compressor plug 2 to a switched +ve to operate the relays in the compressor unit. Note that the 40 Amp fuses in the power loom are of the giant size spade type, the small 'normal' type spade fuses would melt with continuous compressor use.
It's also worth noting that this compressor is rated at 100% duty cycle.

Vlad, you don't turn off half the compressor, it'd be a bit like disabling one bank of cylinders in a V8, it'd go like a dog and put excessive strain on the other motor and cause it to burn out.

The current draw of the compressor will determine the required fusing and is usually written on the side of the compressor. As a rule of thumb multiply its current draw by 1 1/2 to get fuse size. ie. if its a 25 amp draw go for a 40 amp fuse :), but make sure you use those big buggers like the main Defender fuses near the heater unit under the bonnet. Use a dash switch with an internal light to feed a fused (you can use a little fuse here) +ve to a relay to turn the compressor on. If you have a compressor like the ARB one discussed you won't need an additional external relay, but if you're using a 'normal' portable type compressor you will need an external relay located close to it.


Deano :)

[VladTepes]

Can't afford a flash new ARB compressor like that one, I'll stick with the bushranger one I have.... Can always upgrade later if needs be.

[Iain_B]

I have an ARB twin motor in my Unimog as an auxiliary air pump and to pump tyres and run air tools etc without running the engine driven compressor.

I measured the current draw at 60A when pumping my air system up to 8.5 Bar.

[marty]

Arb single unit mounted on a checker plate bracket over a tigers air tank
The arb was a show special and came with loom and extension hose ,inflator , inflator with guage, and a really nifty air line surface mount connection .
I pulled the first one apart to see how it worked and dropped all the ball bearings, surprisingly the second one was not expensive I think about $12
The tigers tank came with pressure switch and hoses
I mounted the whole lot in the dead space behind the fridge slide.
One connection point just beside the bottom door hinge in the back. Run through side storage on black widow draw system
Wiring loom to the centre console for switch(it comes with a full loom for lockers if you buy the lockers you get a locker,switch and solenoid all the wiring already there)
50 amp line from battery box to compressor
Hose reaches all four tires from the back, tank is great for blowing filters etc
Can post pics if you like
Marty

[Blknight.aus]

Thanks - 2 switches? Can you turn each half of the twin compressor on/off seperately?

not quite...

a pair of SPDT switches to drive the relay that turns it on or off so you can mount a switch at each of the air outlets.