AMK Compressor and "Normal Height Only" fault, and fix!

**Grentarc** · 30th June 2016, 04:49 PM

On Sunday I got my first "normal height only" message, which surprised me at first as my D4 has the AMK compressor, but after a bit of thought and figuring out when the compressor was installed (almost exactly 6 years ago) and remembering how much use the compressor has had in this time I had a feeling it may just be that the dryer was blocked.
I did a little online searching and found one place in the UK that sells new desiccant and filter pads for AMK compressors for ?19.99, so it must happen enough for someone to make a kit.
I decided to buy some silica based desiccant beads (not crystals) to replace my aging desiccant, and made some filter pads out of some thin felt.

The compressor is pretty easy to remove, I did it via removing the 3 bolts with springs holding the compressor to the mounting plate instead of removing the whole plate - this way I could give my (dodgy) shoulders a rest from time to time instead of having to hold the entire weight up when removing and installing - it does squeeze out if you remove the bolts, then springs and remove it towards the rear of the vehicle and out the side at the same time.

Once removed, the best thing is to put the compressor in a vise (sorry, no photo) as the two T30 screws holding the dryer on were very very tight - no thread locker was spotted, so none was applied on reassembly. The trick is to keep the dryer pushed down whilst undoing the screws as there is a spring inside that keeps the desiccant compressed.

Once the dryer was off, I could see the filters were pretty dirty, and there were quite a few crushed desiccant beads
There are 2 metal screens, one at each end with the filters being on the desiccant side of these screens.

I replaced the bottom screen and filter, filled the dryer with new beads and then placed new filter then screen on top - there are little tabs to lock the screen in place before reassembling with the spring.

I reassembled in the same order as I disassembled and once I cycled the ignition (Suspension fault comes up if you disconnect compressor while the battery is still connected), my suspension works as it should, and I must say, much quicker than before.

The desiccant I bought is this stuff and I have probably enough to do another 4, maybe 5.

**LRD414** · 30th June 2016, 06:21 PM

Good write-up Justin. Any difficulty disconnecting or reconnecting air lines?

Scott

**Grentarc** · 30th June 2016, 06:37 PM

Originally Posted by LRD414

Good write-up Justin. Any difficulty disconnecting or reconnecting air lines?

Scott

Thanks Scott,
No difficulty, I just used a small shifter to undo the 3 air lines as my open ended spanners were on the other side of the car and I really didn't want to get up off the ground again.
The hardest part of the whole thing was probably getting the compressor back in, but that wasn't anything more than maybe 2 minutes work.

**scarry** · 30th June 2016, 07:06 PM

Good write up

FWIW,there is also an inlet filter up in front the left rear tail light that probably could do with a clean as well.Not the easiest thing to get out though,actually a PITA to get out.

**Grentarc** · 30th June 2016, 07:12 PM

Originally Posted by scarry

FWIW,there is also an inlet filter up in front the left rear tail light that probably could do with a clean as well.Not the easiest thing to get out though,actually a PITA to get out.

Yes, it could probably do with having a look at, as the vehicle is 6.5 years old now

**crawal** · 30th June 2016, 07:15 PM

I rebuilt my old Hitachi compressor using one of the kits from the uk , hardest part was the top bolt.rebuilt on the kitchen bench works a treat , good write ups on the Disc 3 site.

**Grentarc** · 30th June 2016, 08:05 PM

Originally Posted by crawal

I rebuilt my old Hitachi compressor using one of the kits from the uk , hardest part was the top bolt.rebuilt on the kitchen bench works a treat , good write ups on the Disc 3 site.

Luckily my compressor isn't to the point in needing a full rebuild - I did note that when it was restricted to normal height that the compressor was not noisy at all, so was hoping at the time it was just the dryer becoming blocked.

**PerthDisco** · 30th June 2016, 08:41 PM

Originally Posted by crawal

I rebuilt my old Hitachi compressor using one of the kits from the uk , hardest part was the top bolt.rebuilt on the kitchen bench works a treat , good write ups on the Disc 3 site.

Was called Landyair now called 4x4airseals. Not expensive at all.

I did same and top bolt very awkward. I was in a pit under the car and don't think you could do lying under. Need a universal on extensions to get the socket over the top onto the bolt. You need to be right under it to have any chance of seeing what you're doing. Good videos online. New unit looks much easier.

Drug squad had a good look at the package filled with white crystal looking desiccant.

There is a rebuild kit for the piston side also.

Mine is MY08 and all pipes came out with some lube spray with a little fight. You have to know the trick to push in and hold the collar.

Original unit still going strong. Well worth cleaning out behind the cover also.

**LRD414** · 30th June 2016, 09:07 PM

So is the normal height only warning just based on taking too long to raise (time-out) or a thermal switch?

Scott

**Grentarc** · 30th June 2016, 09:16 PM

It was coming on without any height change requests, and have been told it is usually from a failure to reach a specified resivoir pressure/it can tell that the pressure is not rising fast enough. I prefer this over thermal cutout as it means compressor life is going to be better than if it is overheating regularly.

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