Symptoms
Slow height changes, suspension faults, a compressor that gets very hot and slows before cutting out with an error. One DISCO3.CO.UK owner's unit reached 90°C in about 90 seconds.
The fix, step by step
- Owners rebuild the original Hitachi with a piston glide ring, fresh desiccant and filters and an aluminium dryer cap, or fit a complete new unit.
- Don't wait: a failing compressor lets the dryer's silica turn to dust, which can reach and damage the valve blocks.
- Expect seized unions at the dryer (penetrating oil and time), use silicone grease on the O-rings, check the bracket bushes, and fit a new relay.
- Converting to the later AMK compressor is a factory-approved upgrade but needs a software update.
Tools & part numbers
- Sockets, penetrating oil, silicone grease, push-fit couplings if pipes must be cut
- compressor overhaul kit JPO500010
- dryer VUB504700
- relay YWB500220
Where to buy the parts
Hunting a used or discontinued part? Search eBay Motors for Land Rover LR3 / Discovery 3 parts →
Rated for a competent home mechanic with a decent tool kit. Confirm torque figures, fluids and procedures against the factory service manual for your VIN, support the truck on stands rather than a jack, and work at your own risk (disclaimer). Some parts links are affiliate links, which pay us a small commission at no cost to you.