How To Install On Board Air Compressor

On Board Air Compressor

Today I will be working on my onboard air system project

on my Dodge Ram 1500. It’s about time to install the compressor now

draws up to 38 ampere with the maximum operating pressure of 200 PSI

this thing’s maximum airflow is at 3.5 cubic feet per minute

and it seems to be built pretty solid and weighs about 20 pounds

the unit has 2 brackets with four rubber buffered holes on it

for an easy bolt-on installation. It came with the pressure switch

that’s going to turn the unit off at 200 PSI

and turn it on as soon as the pressure in the tank drops under 165 PSI.


Also there’s this relay to connect the compressor to the power supply.

And then we have the air filter unit to keep dirt and dust from going inside the compressor.

It comes with two spare filters which is kind of nice.

The filter can be screwed directly onto the compressor

or you can use a hose to put the filter somewhere clean and dry.

These are the small bolts that are included to mount the compressor.

I ordered some extra ports for the connections.

There is this 1/4 inch T piece which I want to put directly behind the check valve

so that the pressure switch can be mounted close to the compressor.

You could also put it onto the tank but this way I don’t have to run so many wires.

Then I got these screw-in-quick-connectors for all line connections.

These are just screwed in and then you can just slide in the poliamide line into the blue side.

The airline’s outer diameter is 8 mm and the inner is 6 mm.

According to the manufacturer it can be used for working pressures up to 275 PSI.

A good thing is that you can easily add outlets to the line by putting in one of these T-pieces.

For air horns or what ever.

I will be using this teflon tape to all pneumatic fittings to avoid air leaks.

The power wires on the compressor are not that long.

If you want to mount the unit further away from your battery, you have to get extra wires.

Befor wireing i want to find a good spot to mount the compressor.

I dont want to put it in the truck bed since it will be in the way

Putting it underneath the truck would expose it to dirt moisture.

Therefor I decided to install the units somewhere in the engine compartment.

I have this cold air intake here in the front, behind that there’s the control unit and the evaporator of the propane system.

Above the units would be enough space to bolt the compressor to the fender.

But because i want to avoid drilling into the metal of the vehicle, i think that this would be a really good spot here.

The air filter box it made of metal and pretty stable.

The compressor would sit pretty high right under the hood,

which helps to keep dirt moisture away from it.

Also the install would be easier here through a good accessibility from both sides.

Okay this is where it is gonna be so I start to bolt on the compressor.

I removed as existing screw in the corner and use the whole to attach the compressor.

Then the other three holes can be marked for drilling.

That way I make sure that all the holes match well later.

the drill I’m using this just a little thicker than the screws so that they don’t have play in the hole later.

So I mark where to drill, and then removed the compressor so that I have enough space to drill the holes.

and now trim the edges with the larger 10 mm drill.

I make sure that no metal chips or dust remains in the engine compartment to avoid rust.

Now the compressor with all four screws can be mounted.

Alright, the compressor now sits nice and tight at the back of the air intake box.

Now I’ll take care of the airline connection to the tank,

which is located on the passenger side on the on the underbody.

I did a explain about the tank install, you’ll find the link to that at the end of this explain.

The viair unit comes with a check valve already installed.

It prevents the air from pushing back into the compressor when the air tank is filled up.

Now I screw that T-piece on there with teflon tape.

On the other end of the T-piece I put a quarter-inch quick connector.

The pressure switch is now put in the middle, wrapping it nicely with teflon tape to avoid annoying leaks.

I screwed in and tighten it up a little.

Now I’m running the line to the tank, by sliding it on the fender all the way under the truck.

The air tank has 3/8 inch threaded connections.

I screw in one of these angle connectors and tighten it.

Now the line can just be plugged in.

I am now cutting the line to the right length using these pruning shears,

since I don’t have any professional air hose cutters.

Not pinching the line too bad will avoid leaks at the round plug connector later.

It’s time to screw the air filter onto the compressor.

To open the housing you can use a small screwdriver if you need to change the filter.

I removed this little nipple here and screw tha filter on.

Make sure the filter sits on nicely and don’t overtighten it since it has plastic threads.

Now it’s time to take care of the power supply.

For that I first put up 5 mm thick red wire from the battery to thecompressor.

I’m running it together with a small dual wire over to the other side and secure it with zip ties.

The wires disappear nicely behind this weather strip.

I am adding a fused to the positive wire,

and then prepare the end for clamping it onto the battery later.

Now I go over and connect the black negative wire coming from the compressor to the frame of the truck.

For that I use an existing little bolt there next to the propane ECU.

I go on and take the end of the red wire that that i just ran to the battery and solder it on to the relay,

pin 30, you see a diagram of the used relay in the corner of the screen.

Now I solder the red wire that’s attached to the compressor onto the pin 87.

Only wires that are missing now are the ones that work the relay.

So i solder the thin dual wire that i ran behind the weather strip to pins 85 and 86.

Polarity doesn’t matter for now.

Now i can run the dual wire to the pressure switch and cut open on of the wires and connect both ends to the pins of the pressure switch.

Having it solderned on the dual wire is now being ran all the way under the dashboard.

Here i got this little switch that I can control the compressor with later.

this switch again is connected the way that it only gets power with the car ignition on.

So now i connect to prepare power cable to the battery.

Then I use zip ties to secure all the air hoses and power lines.

That way nothing is hanging around in the engine compartment and it looks a little nicer.

I can finally run the compressor for the first time.

Seems like everything’s working as it should.


Source : How To Install Onboard Air Compressor

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