Compressor wiring ? Relay ?

I'd grab a 40 amp 4 pin relay and locate it near the compressor.
Do you have a H/Duty cable running to a power socket in the rear of the vehicle as the compressor will draw a few amps.

What I did was splice into the power supply I have in the back of the wagon. That wire runs to one of, for a want of a better word, slave terminals of the relay. I then ran a small wire to a switch then back to the master circuit of the relay, the other side of the master circuit went to earth.
This will leave one terminal that is the other side of the slave circuit that runs to the + cable on the compressor. The negative on the compressor is then just run to a good earth.

What happens is that there is always power to one side of the relay, and one side of the switch. Flicking the switch energises the relay which in turn lets a large flow of power through the slave circuit to the compressor, without overloading the switch.

Not the best description, I know (and I am sure I will be corrected ;-) ), but mine works as does the pressure switch I also wired in at the same time. If you can decipher the diagram on the side of the relay and take note of the numbers on the pins, it will help you work out whet you are doing.

Here is mine, just finished yesterday. Doesn't show the wiring though. I installed a guarded switch (Rice racers call them a missile switch, and have pushed the price through the roof), to stop it being turned on accidentally.

Hi aeiou

Yes a 40amp relay and you can tap into your wiring with a wire tap.





Regards

Derek

Dave, Sounds very similar to the set-up I've had in my Patrol (until recently, when it's all been pulled out ready to fit out the new Chevissan).

The relay is required if you want to mount a separate switch in the cab area and should be mounted close to the compressor. However, if you just plan to have the compressor mounted so that you have to use it's own switch, then you won't need a relay.....but in any case you'll need a 40 amp circuit breaker near the battery.

Cable size ; the bigger the better....I would say 8mm minimum, double sheathed would be best.

What's the reason you can't just use the wiring already on the compressor, remove the aligator clips, run it to the aux battery and install another fuse close to the battery as per normal safety practice?
You can then use the factory switch on the compressor as normal.

I'm sure I'm missing something as to the reason you go to the trouble of new wire/relay/switch etc. but this is what I did and works fine.

The wiring that comes with the Max Air is obviously up to the job, as is the switch on the comressor. All you need to do is add in a fuse or circuit breaker close to the battery as the factory fuse is too close to the compressor.

I am by no means an expert on 12V as you can see, however am just curious as to the reasons behind the new wiring etc.

Cheers

I wired mine in with a relay as it has a pressure switch in the circuit.
Pressure switch is only rated to about 10 amps, so the pressure switch runs the relay (via a manual switch) and the relay runs the compressor.
You could just run a cable directly to the compressor, but if you want a remote switch and minimal voltage drop then I would recommend a relay. The other thing is I don’t think that the insulation on the cabling that is supplied with the compressors is up to being routed through the bodywork.