OBA -> On Board Air Mega Thread & BS

Just mounted a Viair 2lb tank near the spare tire. Now I need to plumb to the ARB Twin compressor and to my quick release mounting spots. If I install a pressure gauge should it be installed on the compressor or the air tank? Also Any recommendations on what type of tubing I should use? Thanks for any suggestions!

 

You can put the pressure switch at the tank. Also install a check valve at the compressor and a blow off valve at the tank.

 

I like the use of unistrut

 

OK. I need some serious help here.

I have the ARB Twin compressor. It is mounted in a Slee Bracket next to the windshield washer tank.

A few months ago something happened where the compressor would not shut off; not even if I flipped the OFF switch in the cab. It kept running and running until the pressure valve blew on my air tank. Then it ran until the tanked filled back up to normal pressure then stopped as it should.

A few days later it did the same thing, only this time it would not shut off at all; it just kept overfilling the tank, blowing the pressure valve and the doing it all over again and again. Finally, I had to disconnect it from the battery altogether.

Then we had a semi-warm Saturday in February so I decided to do some troubleshooting and see what I could figure out. After some tinkering I discovered that only one side of the compress was not shutting off; the other side shut off just fine. So for the time being I decided to just disconnect the power wires into the bad side. The good side continued to do an adequate - if slower - job of keeping the tank full.

After some on-line research my best guess was that the relay that controls the bad side might be stuck in the closed position; thus never allowing the compressor motor to shut off.

OK. That makes sense.

So today, I unmounted the compressor from the truck, disconnected all the cables and the air hose, removed it, tore it apart, replaced the suspected bad relay, and put it all back together.

Now NEITHER side will work. When I switch it on, it just sits there. [Insert WTF? here]

The 40-Amp fuses in the cables from the battery are both good. The two heavy red wires on the plug for the wiring harness are both hot so power is getting to the compressor itself. But apparently it is not getting to the motors. Another interesting thing is that the 3-inch fan on the compressor housing right near the relays isn't running either.

I tried temporarily running a jumper wire between the the two wires that plug into the pressure valve, as well as leaving both wires disconnected for a test just to see what would happen, which was nothing.

Right now I have the compressor hooked up to the truck, though partially disassembled in other to "bench test" it. Nevertheless it simply will not come on.

So I'm desperate. Any suggestions on where to go from here?

 

There are 4 items that turn it on/off:
On/off switch
2 relays
1 pressure switch

Along with passives:
Main fuse
Switch power fuse
Connectors
Wiring

You can test relays by applying 12V and listening for the click
You can test the switch with a dmm or see if it works on another circuit
Only way to test pressure switch is connected to pressure. (Edit - with no pressure it should be on = very low resistance measure with ohmmeter)
Fuses are obvious.
Check the connectors for heat damage
Wiring should be inspected for heat damage as a precaution since fuse should fail first

 

You can also bypass all of the above and hot wire it directly to battery to see if the motors still work.

 

Actually, I did do that. No difference.

 

Thanks for the suggestions.

All the fuses appear to be good. No smell of burned wires.

Relays tested straight off the battery and they work.

No way to put pressure on the pressure switch right now, but it does ohm-out at very low resistance.

As I said earlier, one side was working fine until I took it apart yesterday. Now nothing.

Now, Here's a question.

Referencing the color-coded arrows, the Red wires (#1) do have power all the time since they come from the battery.

The adjoining Black wires show a good connection to ground.

Small Black wire (Arrow #3): What does it do?

When I switch the compressor on from inside the cab, is this Purple wire supposed to go hot? Because if it is, it's not going hot.

TIA!

 

@Salty_Dog I’m guessing you know how to use a meter since you said you ohm’d it. I would check for continuity on the compressors since you said you have power at the cables. Then check continuity for your grounds.

 

If it worked before and doesn't now indicates either an assembly error or possibly a wire pulled loose from a crimp inside one of the plugs or if there's a bad supply or ground connection.

 

Does the compressor unit have to be mounted (i.e., bolted down) for grounding purposes?

 

I assume not because it has ground wires straight to the power source.

 

Right. The circuit grounds with the wires not the compressor bolts. Check both compressor (touch the power and ground for one compressor. Then the other) it should read some resistance. If the meter reads OL (open loop) then something is wrong with the compressor.

Next I would check for power at the plug.

Then I check the ground cable. Touching one lead at the plug and the other where you grounded it. Again, it should read little resistance. If it reads OL then the ground circuit is open (not grounded).

Next i would check the switch for power (maybe the switch is bad?). And at the relay. And the check ground for the relay.

If all the wiring check out then I would suspect the compressors are bad

I have the single compressor so maybe someone with the twin can chimy in.

Hope this helps.

 

Please excuse my noob electrical question. I got an ARB twin and just got it mounted in my 3rd gen....now for wiring it. The main power harness that comes with it has 2 inline 40amp fuses.

I have a dual battery set-up with all accessories running off aux battery, 90% of them are run via a blue sea fuse block and 10% are add-a-fuse.

My thoughts for possibilities of powering are:

a) get large enough ring terminals to fit the wires (I think they're 8 gauge) and attach directly to aux battery terminals
b) add ring terminals and attach as is into blue sea fuse block (would require 2 powers, each with 40 amp fuse)
c) cut out the inline fuses from the harness and attach to blue sea fuse block with a 40 amp fuse per power line -- this seems to make the most sense since b seemed kind of redundant, though the in-line fuses they come with seem way beefier than the ones in the fuse block?

Appreciate the assistance!

 

Go straight to the battery. Blue Sea panels are rated for 30 amps max per circuit.

 

As said above, straight to the battery. If I remember correctly, that is the install instructions from ARB. Mine is wired directly to the secondary or 'house' battery.

 

^^^What he said.

 

Anybody know where I can find a drain valve like this, but in stainless steel rather than brass? Everytime I want to drain my air tank I end up replacing the whole valve because it gets corroded from exposure to the elements, road dirt, salt, water, etc.

Thanks.

Edit: Forgot the picture:

 

Some accessories( like winch or twin compressors) draw so much current that you should have the motor running when they are in use and you want them drawing load from as close to the alternator as feasible(that is usually the batteries terminals). If your second battery is in the bed then that means connecting to the stock battery location.

 

Like "which" drain valve?
1/4" pipe thread or 1/2"?