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Tips & Tricks: What to consider when working on air suspension

By autotech-nic on June 24, 2020

While working on the air suspension system is generally not rocket science, Arnott provides some quick and easy guidelines to smoothen the repair.

Safety and preparation

For your safety it is strongly recommended that you wear protective glasses, hand gloves and ear protection. The pressure in an air suspension system can be up to 18 bar! Verify that the pressure has been released and that the power supply to the compressor is disconnected before disassembling the air hoses and components.

It is important to be aware of all necessary safety measures when installing a new air suspension component. This includes proper lifting and immobilizing of the vehicle (and of any stored energy) to prevent personal injury or damage.

Visual check

If a vehicle drops more than 2,5 cm overnight there is a leak in the system. Leak detection often only requires a water and soap spray – bubble will indicate the leak. If the car is lower in one corner, or the car is not levelled, this can also be cause by a defective valve block.

A burned out compressor can be confirmed by smell, and/or the colour of the metal body. Brown- coloured labels on the compressor unit are also easy-to-see indicators.

Depressurize the system

Depressurizing the system can be done either at the compressor or the air bellow side. Never fully remove the air fitting at once, but slowly remove to relieve the pressure. Depending on the vehicle’s make and model, a diagnostic tool is needed to activate the solenoids to depressurize the air bellows. You can recognize this by the presence of a connector on the air spring.

Jack mode

Check if the vehicle features a special “jack mode”. If present, use it to prevent the air being released from the bellow when jacking up the car. If not present, the car can be jacked without any precautionary measures. Some systems automatically recognize that the car is jacked and retain the desired amount of pressure in the air springs.

Inflation issues

Never fully lower the car with the lifting device when the air suspension system is depressurized. The air spring could unfold incorrectly and the crimp ring can dislodge. Besides, an aging compressor might not be able to produce enough pressure to raise the car from 0. The relay could get damaged, or in worst case the compressor could burn out in its attempt to pressurize the system to the operational level. The air springs should be mounted the way they came out of the box. Do not stretch them or pre-pressurize them to make the installation easier. During inflation it could fold out incorrectly and get damaged.

Tightening the VOSS connector

VOSS connectors usually do not need tightening. Ignoring this might damage the thread which can cause air leakage. Respect the manufacturers torque specifications at all times. Over torque can result in damaged or broken threads.

Do not just replace, find the root cause.

Always replace the relay when mounting a new compressor. It is likely that the old relay has become “sticky”, causing the (new) compressor to continuously operate (pump air). This will eventually lead to a burned out compressor.

Remind yourself that a compressor is usually not the actual cause of a non-functioning air suspension system, but rather the consequence of a large leakage in another part of the system. Therefore, making the correct diagnosis is crucial. Check all lines, connections and air springs for leaks after the compressor is working again.

Struts and shocks

Critically inspect the air suspension strut or shock absorber for function and oil leakage when replacing a leaking air spring. Oil deteriorates the rubber of the air bellows and drastically lowers the lifespan of the part. Secondly, if the shock absorber is no longer performing its task properly, the air spring overworks and will get damaged quickly.

Diagnostic tools and software updates

After the test drive, make sure no fault codes are re-entered in the system. It is recommended that you check the height sensor parameters with a diagnostic tool and adjust if necessary. This ensures the correct height at each corner of the vehicle enabling the system to respond correctly to inputs when driving. Additionally, perform a wheel alignment when the shock absorber or strut is replaced.

ALWAYS perform a dealer software update if this is required in the installation manual. Ignoring this will cause the compressor to not work as it should, possibly leading to a mal-functioning or burned compressor.

This information is provided to you by Arnott – Air Suspension Products. With more than 30 years of experience in engineering, designing and manufacturing high quality air suspension components for the aftermarket, Arnott is the technical expert when it comes to air suspension systems. Arnott’s products are produced with high-quality, OE components offering exact form, fit and function. Each product is extensively tested in our American and European facilities and custom-tuned to suit the specific vehicle make and model before being produced.



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Autotechnician is a magazine published nine times a year, delivering essential information to independent garage owners and technicians in the UK. Delivered both digitally and in print, autotechnician provides readers with technical, training, business advice, product and news, allowing our readers to keep up to date with information they need to run and work within a modern workshop.
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