The valve block is a small but significant component of the air suspension system.
Symptoms that seem to point to a leak in an air spring might indicate a defect in the valve block.
The valve block takes care of the distribution of pressurised air. The general objective is to use the pressurised air as efficiently as possible, so the compressor runs as little as possible. This prevents overheating and keeps energy consumption low.
Over time, the solenoid valves in the valve block can become sticky or blocked by small particles that circulate through the system during operation. For example, when an aging compressor breaks down, the valve block can become damaged too. Small metal particles can block the solenoid valves and disturb the air distribution causing the vehicle to be lower in one or more corners.
The valve block is also involved in the release of excessive air pressure. If needed, the solenoid valve towards the air compressor is opened. The pressure is released through the pressure release valve on the compressor. In cases where a vehicle stays “locked” on a certain ride height, first check the function of the pressure release valve on the compressor before diagnosing a faulty valve block.
If an air compressor is no longer running, the usual suspect is often the compressor or a faulty relay. It might be the valve block. The air suspension pressure sensor is located inside the valve block, not in the compressor. If this sensor isn’t working correctly, the signal for activating the compressor stays out and pressure is no longer built up.
If the dryer no longer has the capacity to keep moisture out of the system, the valve block can corrode internally. Freezing temperatures can also cause the moisture inside the valve block to freeze and stop functioning.
One last thing to keep in mind is normally the airline from the air compressor to the valve block is unpressurised if the compressor is not running. This allows the compressor to start easily. If for one of the above-mentioned reasons this airline stays pressurised, much more heat is built up each time the compressor is activated. This could lead to a burned-out compressor.
Even though it is small, this significant component of the air suspension system deserves some attention – especially after a compressor replacement.
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