Citroen experts only please, or someone who is had the same problem. The suspension height 'regulator' fails to recognise the 'normal ride' setting. Low setting is fine, off road setting is fine. It will go from low to high, and high to low and that is it. It wo not go from low to normal, or high to normal. What does the accumulator sphere do, and is the anti-sink valve the same thing as the accumulator sphere.Is there an accumulator sphere on the front as well as the back, and if it is a different thing, does it have a anti-sink valve on both the front and the rear. Is the LHM fluid level crucial to this problem and how do l get the level between the two red rings on the glass dome on top of the reservoir? I've never seen the level between the two red rings no matter what l do! Also, the front end occasionally sinks noisily when l turn the engine off (maybe once in 20 times l switch off) Citroen suspensions a problem....l should say so! I am out of space, so more innext question

Sounds to me u may have more than one problem here. The accumulator sphere stores reserve pressure for the suspension/braking system. Depends on the age of ur car but all Xantias from around L or M reg onwards were fitted with anti sink suspension. You have 2 height correctors, one front & one rear & 2 anti sink valves (again 1 front & 1 rear), u have ur 4 suspension spheres & a main accumulator sphere at the front of the car (it is attached to the front of the gearbox bell housing). There is also an accumulator sphere close to the rear height corrector, not sure if this is linked to the brakes, suspension or both but i've never known this particular sphere be changed on any car.

The accumulator sphere stores reserve pressure so the system still works after the engine is switched off. If u had no reserve pressure & the engine cut out u would have poorer suspension & more importantly no brakes. The accumulator ensures the system still works for a time after the engine driven pump has stopped working.

The anti sink valve is tube shaped, it has several pipes going into it, at the rear it is located next to the height corrector, at the front it is located under the LHM tank (this one is difficult to see). The object of these valves is to keep the car sitting at normal ride height when the engine is switched off.

The 2 height correctors r easy to locate, they r attached to the centre of the front & rear subframes. They r linked to the anti roll bars, they r adjustable & maintain the car at the correct height no matter how much weight is in the car. If the front or rear height is too high or too low this can affect brake performance.

To set the fluid level, place the suspension in high with the engine running, top up the level until the gold disc is between the 2 red rings in the glass float. You may need to flick the glass with ur finger in case the float is sticking. When carrying out a fluid change the tank should hold between 3.5 & 4 litres of LHM. Do not forget also that if ur brake pads r low this will also cause the fluid level to drop. As long as the fluid level is not dangerously low though (so the warning light comes on) this should not affect the system

If u can not get ur suspension to sit at the correct height u may have a seized height corrector (the rear one is more common), each height corrector is linked to the anti roll bar by an adjustable clamp on the roll bar & a small plastic link rod. Apart from the height corrector seizing the clamp can break & the link rod can wear away & become detached. If u replaced a faulty clamp & link rod & the problem persists then the height corrector is probably internally seized & would need replacing also.

If ur suspension occasionally sinks at the front then u may have a problem with the anti sink valve. Or there may be a problem with the accumulator sphere. To test the sphere, have the engine running & ticking over. Pump the brake pedal & keep it firmly pressed, if u get a loud clicking from the front of the car (you sometimes get it when operating the steering as well) then i'd say the sphere needs changing.