What is the pressure in air suspension?

In receivers of different car models there can be different pressure. In the rear air suspension one pressure, in the front – pressure will be higher. On average, in the receiver of most cars, the pressure ranges from 12 to 13 atmospheres. For example, in Range Rover Discovery car, the pressure can reach 18-20 atmospheres. If the air suspension compressor is not capable of injecting pressure over 17 atmospheres, the system shows an insufficient pressure signal. There were cases when the compressor did not pump up to 20 atmospheres, but only 18 were injected. This was no longer enough, and the system signaled an error until a pressure of 20 atmospheres was provided.

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Essential tips for owners of air suspension vehicles while driving. What can happen with the air suspension on the road, and how to act in such situations?

During the long trip, the car completely fell on the bump stops from all sides. The driver slowly drove by himself to the nearest service station. Diagnostics revealed that the height sensor had failed. Water got into the sensor, so it gave out incorrect signals, the «brains» saw this problem and lowered the air suspension and switched it to emergency mode.

Replacement of sensor has solved this problem. If a similar situation happens while driving, either slowly continue to drive on the bump stops to the service station or call a tow truck. For example, the Audi Q7, Porsche Cayenne and Volkswagen Touareg air suspensions are high, so even when the car lies on the bump stops, the wheels do not reach the arches. The ride will be tough, like on a cart, but possible.

In the case, with a Mercedes W220 car, it is better to use a tow truck, because at the slightest turn of the steering wheel, the wheels will cling to the arch. You can go on a straight road, but the steering wheel can be turned to a small angle. In this case, it is suggested to turn off the compressor. This can be done by switching the air suspension to the jack mode or disabling the relay/compressor fuse, but everything will depend on the specific vehicle.

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How to get to the compressor relay on Audi Q7?

The compressor relay is located under the steering wheel. It is necessary to remove the lower protection, under which the relay unit is located. There are several relays, one of which is a compressor relay. There were cases when by mistake they replaced a wrong relay, which led to the failure of the air suspension compressor, as the native relay was jammed, and the compressor worked even with the shut down engine. You need to be very careful when you are replacing the relay.

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How to check compressor temperature sensor on Audi A8 D3?

The simpliest is to check with a computer using a specific program. You need to enter the command section, find the compressor temperature sensor and check the temperature. If it has stucked when overheated, it will show a constant temperature in excess of 120-130 degrees. That is, it will show a constant high temperature. Because of this, there will be an error and the system will not work.

If you check without a computer, you need to remove the protection, disconnect the connector from the sensor, take a multimeter, set the selector to measure the resistance with a threshold of 20 kOhm and measure the resistance of the temperature sensor. If the sensor is in good condition, the multimeter will show resistance from 14 to 20 kΩ. Sometimes, resistance can go as high as 21-22 kΩ. Everything will depend on the air temperature outside. If the compressor temperature sensor is jammed, the multimeter will show a resistance of about 1000 ohms. If the sensor has stuck on overheating, the multimeter will show a resistance of approximately 300 ohms.

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Range Rover compressor does not shut down

The two most likely causes are:

  • Either the relay is jammed (soldered contacts), then even with the engine shut off, the compressor will work. In this case, you must either remove the battery terminal; remove the compressor fuse or remove the relay itself to turn off the compressor;
  • Maybe compressor is dead. But then the system should give an error. Because, as practice has shown, if the compressor is working and there is no pressure, after a certain time the compressor will turn off and error appears.
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Scheme, how to do well without Audi Allroad compressor

An additional input with a nipple is mounted in the receiver. The car owner periodically pumps the air suspension system with a usual compressor, raising the car to the desired level. So he drives like on a springs in one position, most often in the second position. If the system is unpressurized, during some time the air will go out, then car lowers to the first position, and the driver again must pump air into the pneumatic system with any compressor capable of providing at least 8 atmospheres pressure in the system.

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