I know these problems have been discussed here before, but I couldn't find a similar case.

Problem is that the system first went inactive intermittent. Now it has been inactive permanently for the last month. The level stays spot on and there are no leaks, but you can't change the ride height.

With DIS it's only showing one fault code for low accumulator pressure. The accumulator showed ~8 bar. The treshold seems to be 9 bar. If the pressure drops below the system is inactivated. I activated the compressor with DIS and it started correctly and the pressure in the accumulator raised correctly. After this activation the vehicle itself activated the compressor and pressure went to correct 15 bar. The pressure was constant, no leaks. Now we started to lower and raise the vehicle. For some odd reason the compressor was not activated and the accumulator dropped below 9 bar and the system was inactive again. I also checked the compressor activating information. It was inactive. So the system was not even trying to activate the compressor even if the pressure in accumulator was dropping. When ever I activated the compressor with diagnostics it started correctly, ruling out relay fault.

So I'm stumped. All the components seem to work correctly but for some reason system is not activating the compressor correctly even if the pressure in accumulator drops. Any thoughts? Control unit fault? I've read that there has been problems with these EHC2 control units, but what kind of faults were they having?