Teki
Member Since: 18 Mar 2023
Location: Stockholm/Umea
Posts: 4
  
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| Car deflates with RCM fuse in place, but holds air otherwise |
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Problems:
-Car has "suspension fault" amber light come on soon after starting car.
-Car deflates (front first) both on drives and stationary
-Car does NOT deflate when the fuse 35 (rideheight control module) 5A fuse is removed!?
Fault code:
-Pressure increasing too slow when filling reservoar.
Done:
-Removed air tank and checked for integrity and it is air tight.
-New front valveblock
-New front right strut (was sagging front right corner on "suspension fault" drives.)
-About a year ago i removed center valve block and compressor, no faut found.
Thesis:
Obviously this could be a worn out compressor failing to fill the system. However, the leak in the system only occurs when the RCM fuse is in place. So both front and rear valve blocks and struts seem to be airtight since it holds its height when RCM fuse is removed.
And since it is showing a leak in the middle somewhere, where could this be? Are there two valves for letting out air on this system? One release valve on the AKM compressor? And is this one only for venting internal pressure of the compressor? One venting valve in the "middle" valve block?
Do these tend to get stuck or not seal?
Going to take compressor down and also the center valve block to see if i can clean it out and make sure everything is moving freely.
If this does not fix the problems, is my best bet valve block or compressor as first buy, or both?
Tips and ideas are welcome, thanks.
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 2nd Apr 2024 12:15 pm |
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Globetrotter448
Member Since: 21 Mar 2017
Location: Londonderry NSW
Posts: 1818
 
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If it holds air with the fuse removed, then you should not have a leak. To me, it sounds like a height sensor problem. I would check the one on the front where the airbag was changed before checking others.
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| 10th Apr 2024 8:34 am |
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Teki
Member Since: 18 Mar 2023
Location: Stockholm/Umea
Posts: 4
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Yes! I was reqding up on the height sensors and that they can become bad over time! I will look into getting them recalibrated. I think im in for a new compressor though since i still get the pressure filling too slowly.
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| 10th Apr 2024 9:20 am |
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Globetrotter448
Member Since: 21 Mar 2017
Location: Londonderry NSW
Posts: 1818
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Filling too slowly can be many things like the centre valve block or just the desiccant in the compressor.
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| 10th Apr 2024 9:30 am |
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Teki
Member Since: 18 Mar 2023
Location: Stockholm/Umea
Posts: 4
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Thanks for the input!
Yes! i took apart the center valve block and cleaned it out and it looked good internally. However i found one of the connected pipes had a broken O-ring, so i replaced the whole brass fitting.
Since then, the car is not lowering itself with the fuse pulled or not, but it sits 1-2cm lower on the right side compared to the left, even when "just lifted" so i think i need to recalibrate the sensors. I bet they are out of spec from having the malfunction for so long.
I think i will be ordering a new compressor, since the exhaust valve looks good, and the dissident also does not seem to be a problem, i think its just worn. And rather than changing it and tying to rebuild, this one has done its time already. So i will be ordering a new AKM compressor. And if i still get a fault i think the center valve block is next.
Regarding the center valve block being the problem: There is no pressure sensor in the reservoir, only in the valve block and that is always seeing pressure between compressor, front valve block and rear valve block, so when the car is saying that the reservoir is filling slowly its the reffering to the whole gallery pressure, and if the reservoir valve were to stick closed or partially closed, the pressure should increase faster rather than slow. So my bet is that the compressor might be worn. That or there is another leak somewhere. 
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| 12th Apr 2024 11:48 am |
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