Electronic Components with Fitting Position Front and Rear, Front Axle

The electronic components are what turn a set of airbags into a system you can actually use from the driver's seat.

An air suspension compressor supplies the air, valves decide where it goes, sensors and controllers decide when, and gauges tell you what is happening. Get these right and adjusting ride height takes seconds. Get them wrong and the airbags themselves are only half a solution.

What the Electronic Components in an Air Suspension System Do

A complete system has a handful of parts working in sequence.

An air suspension compressor draws in atmospheric air and pressurises it. On many systems that air goes into a storage tank, so pressure is available instantly rather than waiting for the compressor to catch up. A valve block routes air from the supply to each air spring through a series of solenoids, and the same block releases air when the vehicle needs to come down.

Air lines carry everything between those components, with fittings joining them and a drier removing moisture on the way through. Pressure switches tell the compressor when to run and when to stop. Gauges and controllers give you the information and the control.

On factory fitted systems, height sensors at each corner report where the vehicle is actually sitting and an electronic control unit adjusts pressures automatically to hold it there.

Air Suspension Compressor Duty Cycle, 12V and 24V

Compressor choice matters more than most people expect, and duty cycle is the specification to look at.

Duty cycle describes how long a compressor can run before it needs to rest, usually expressed as a percentage of a given period. A unit rated at 25 percent can run for a quarter of the time and needs the remaining three quarters to cool.

That figure is what decides whether a compressor survives its first few years. A system with a large air tank, or one where pressures get adjusted frequently, asks the compressor to run more often, and a unit chosen on price rather than duty cycle will be working beyond what it was built for from the day it goes in.

A 12 volt compressor suits most light vehicles, while 24 volt units cover trucks and commercial applications running that electrical system. Output is rated in litres per minute along with a maximum working pressure, and both need to suit the volume of air the system holds.

Heavy duty units exist for commercial vehicles, buses and coaches where the system works continuously rather than occasionally, and they are worth the difference on anything that does serious work.

Single and Dual Air Suspension Compressor Setups

Most systems run one compressor, which is adequate for a load assist setup adjusted a few times a week.

Two compressors appear on larger systems for two reasons. The first is fill speed, since a system with a big tank or four air springs takes considerably longer to pressurise on a single unit. The second is redundancy, because a compressor is the component most likely to fail, and a vehicle that relies on air for its ride height is in an awkward position without one.

For a touring vehicle a long way from a workshop, that redundancy is worth thinking about. For a ute with load assist airbags that can be topped up at a service station, it is not.

Valve Blocks, Solenoids and Air Management

The valve block is where air is directed, and the level of control it gives you is the main difference between a basic system and a managed one.

At its simplest, a manual valve lets you add or release air at each spring by hand. Step up from there and solenoid valves do the same job electrically, triggered by a switch on the dash.

A full air management system brings the solenoids, pressure sensors and a controller together so pressures can be set from the cabin, stored as presets, and recalled. That means a loaded setting and an unloaded setting available at the press of a button rather than set by feel each time.

Independent control of each side matters on a vehicle that loads unevenly, which covers most touring setups with drawers, tanks or gear that will not sit centrally.

Height Sensors and Electronic Air Suspension Control

Vehicles that left the factory with air suspension use height sensors rather than pressure alone.

A sensor at each corner reports the actual ride height to a control unit, which adds or releases air to hold the target. Because the system is measuring height rather than pressure, it levels the vehicle regardless of how much weight is in it, which a mechanical spring cannot do.

These systems usually offer several preset heights, from a low setting for loading through to a raised setting for rough ground, with height selected automatically based on speed and conditions or manually by the driver.

When something fails, the control unit typically detects it and drops the vehicle into a protective mode, lowering it and limiting the system until the fault is repaired. That is a warning rather than a breakdown, and it is worth acting on rather than driving around in.

Air Driers and Why Moisture Destroys Compressors

This is the component most often left out, and leaving it out is expensive.

Compressed air carries moisture drawn in from the atmosphere, and inside a sealed air system that moisture condenses, collects at low points, and reaches components that were never meant to see water. It corrodes the inside of air springs, it sits in valve blocks, and it reaches the electrical parts of the compressor.

An air drier containing desiccant removes that moisture before it enters the system. On a vehicle doing water crossings, or simply living in a humid climate, it is not an optional extra.

Draining any tank periodically is the other half of it, since a tank is where water collects first.

Why Air Suspension Compressors Fail

Compressors rarely fail on their own, and knowing why saves replacing the same part twice.

The most common cause is a leak somewhere else in the system. A leaking air spring, a chafed air line or a poor fitting means the compressor runs constantly trying to hold pressure it can never reach, and burnout is the result. Replacing the compressor without finding the leak means the new one goes the same way.

Moisture is the second cause, reaching the electrical components and corroding them from the inside. An air drier and a drained tank address it.

Insufficient duty cycle is the third cause, because a compressor bought on price and asked to do more than it was rated for wears its seals early, and worn seals mean it works harder still.

Air lines fail by chafing rather than bursting, usually months or years after installation, where a line has been routed against a sharp chassis edge or close to a moving suspension component. Fittings fail at installation if they were not seated properly and very rarely after that.

If a system is losing pressure overnight, the leak is usually findable with soapy water at every joint before anything gets replaced.

Air Suspension Gauges, Switches and Controllers

How you interact with the system is worth deciding early, because it affects the wiring and the mounting.

A basic setup uses a pressure gauge at each valve, read while standing at the vehicle. It is the cheapest arrangement and it works if pressures rarely change.

Dash mounted gauges and switches bring the readings and the control into the cabin, which suits a vehicle where the load changes regularly.

Wireless controllers and app based systems replace the panel entirely, letting pressures be set from a phone while standing beside the vehicle hitching a van or loading a tray. Most hold preset heights so a known setting can be recalled rather than judged by eye.

Whatever the control method, a manual backup is worth having so pressures can still be adjusted if a controller fails somewhere remote.

Choosing Air Suspension Electronic Components

The specifications that actually matter are straightforward once you know which ones to check.

Match the compressor duty cycle to how often the system will run, and be honest about that rather than optimistic. Match the voltage to the vehicle's electrical system, then check the compressor output against the volume of air the system holds, since a small unit filling a large tank will run constantly.

Decide whether you need a tank at all. It speeds adjustment and reduces compressor running time, and it also adds weight and takes up space.

Decide how you want to control the system before it is installed, because retrofitting cabin control to a manual setup means running wiring that could have gone in at the same time as the air lines.

And specify the drier and the fittings properly, since those are the cheapest components in the system and the ones that cause the most expensive failures when they are left out.

Fulcrum has been working on suspension since 1976, with 16 Service Centres across Australia and 200+ authorised workshops. Getting the electronics specified, wired and mounted properly is the part that decides whether the system gives trouble, and it is what the network is there for.

Find Air Suspension Electronic Components for Your Vehicle

These parts are designed to run alongside complete air suspension kits, and replacement lines, fittings and valves are available in our air suspension parts range.

Select your vehicle to see the compressors, air management systems, controllers, gauges and fittings available for it, or talk to your nearest Service Centre about specifying a system around how your vehicle is actually used. Everything we supply is backed by our warranty, a fitment guarantee and the support of a nationwide workshop network.