First post as Disco/LR 3 newbie (have had P38 in the past). Hi everyone I'm trying to track down an air suspension fault, and have followed numerous threads online and in this forum, but struggling to tie it down, and looking for any pointers...

Symptom: Start car, compressor kicks in, after about 15-20seconds, throws a Suspension fault on the dash, and more often than not none of the corners will raise if it tell it to, but sometimes they do somewhat randomly (I get the code C1A20-64 pressure increases too slow when filling reservoir).

Background: So, I got the D3 as a project knowing it had some previous work, and a current suspension issue, what I know from the invoices is the D3 has had in 2021:
- New Air Suspension Valve Block
- New Front Cross Link Valve
- New Air Suspension Compressor (having looked it's got the Aerosus label)
(I think the previous owner gave up and sold this on, after throwing so much money at it)

Diagnostics:
my diagnostics so far to try and pin-point the problem....
- when it decides to raise itself which it does a little randomly, but not often, and I pull the fuses to stop the self-levelling to see if any obvious air-leeks, then it'll sit at correct ride-height for over 48hrs no problems, so that tells me, none of the air-bags have leaks.
- have looked over, listened, and sprayed soapy water over the air reservoir and can't see any leeks (but not dropped it to check the top of it yet, but can't hear anything). Also when I monitor it's air pressure, I see it rises quickly to about 850-900Pa, holds that for around 5-10seconds while the compressor is running, and then it'll just drop all the way back down to about 85Pa (when the compressor stops running at the same time), as if it's getting rid of all the air for some reason, maybe by design, not sure.
- have checked the air intake filter (in the boot) and that looks fine
- I can't belive it's air dryer clogged (after less than 2 years and very little use since being installed by the previous owners garage), but i've ordered a new decandescant kit just in case, but it's pushing air into the reserviour quickly (if the readings are correct), so not sure that's the issue.
- I can see the compressor temp rises from about 45 - 55C when activated, which seems about what i'd expect, so not overheating, and not shutting off because to hot
- I can see the reserviour value opens to 100% when the compressor is running, and then closes when the reserviour seems to empty itself, not sure if this relevant, but thought i'd mention it.

I'm now stumped as to what to look for in the live data to help me narrow this down, my guess is it maybe something faulty with the reservoir, but if it's not a leak, what else would it be? or it maybe the rear cross-over block is stuck, but not sure how to test if that's the case before I start rebuilding it.

any help or pointers for what next greatly appreciated... thanks everyone

 

I had similar issues to yourself, and would raise vehicle, pull fuse and it wouldn't drop after a week. In the end the situation was so bad it'd just drop to bump stops for no reason because of the fault. Wife and kids had a great ride home one afternoon not realizing what had happened. You'll find my thread on here, but in the end I replaced a 2 year old compressor and that fixed everything. Not had an issue since. Seemed I had a Friday compressor lemon but was in denial due to it being so new. However, replaced ride height sensors and valve blocks all round as well as testing everything in between.

 

ah, that’s helpful, was there any live data you pulled that helped you decide it was the compressor? I’m wondering if it’s the transfer relief valve, but not sure how to diagnose that. Also my compressor does seem to push good pressure into the reservoir tank and not overheat, hence I’m thinking maybe not the compressor…

 

https://landroverforums.com/forum/lr...-113049/page4/

That's my troubleshooting thread which got me through to conclusion. PITA and still annoys me, but since I replaced the compressor I've had no issues whatsoever.

 

Get a compressor rebuild kit from 4x4airseals, most of the time vehicle raising slowly issues can be a blocked drier/filter.

 

As above, the dessicant and filters can clog pretty quickly. If they are water logged due to excess moisture they can freeze up in cold weather and cause the filling slowly fault. Lastly, knock-off air compressors have been known to fail in just a few months or a couple years.

 

Transfer relief valve? What is that?

 

Thx everyone, I have a dryer kit coming which I’ll give a go, and also a used relief valve (middle air valve block) that I’ll also fit, and see what happens.

 

Just to follow this up… did do air dryer kit, and sort of helped briefly, but problem soon returned, so bit the bullet and installed new compressor (despite current one being only 2 years old) and the problem is now fixed! Thx rich.cash for suggestion.

 

I did the dryer kit to no avail either. Just make sure you have no leaks, otherwise you'll get through your new compressor in no time! Glad it's solved.