I have received a few PM's and emails regarding ARB Compressor Problems, that combined with RME's lacking tech info, motivated me to write up a guise (with the help of the ARB service manual 
)
3 Basic air supply disruptions:
1. Compressor fails to switch on
- a. Electrical fault (most common, usually a fuse, wiring, relay)
- b. Mechanical fault in compressor (rare)
- c. Isolating switch fitted and not turned on (as in a aux. fuse block switch)
2. Compressor fails to switch off
- a. Electrical fault (pressure switch)
- b. Air leak (compressor trying to meet pressure switch req.)
3. Lockers fail to engage when button is presson on
- a. Electrical fault (see part 1)
- b. Sized or leaking solenoid valve (easy to swap, relatively cheap)
- c. Mechanical fault in compressor (rare as mentioned before)
Common Solutions:
1.a & 3.a
- Check the battery terminal is connected
- Check all connections are secure, no loose or disconnected wires
- Check the fuse (system only requires one 30 amp fuse)
- Check pressure switch relay& dash mounted switches
(a simple multimeter/test light can be used for all testing)
1.b
- If mechanical fault is suspected in compressor (return to ARB service center)\
1.c
- Test all functions of isolating block with multimeter/test light
2.a
- Check that pressure switch is functioning using multimeter/test light
2.b
- Air leakage can occur at several locations in the air supply system for a number of reasons.
2.b.1 - Check all connections
2.b.2 - If leak is detected at fittings, remove, clean, apply sealant, and tighten.
3.b
- Solenoid valces (Part# 180102 & 180103) can be disassembled and cleaned.
- Assemble onto compressor using hydraulic sealant (Loctite 569)
- If solenoid continues to fail, replace with nee (tested used) unit
3.c
- If mechanical fault in Air Locker is suspected, remove differential and inspect
)3 Basic air supply disruptions:
1. Compressor fails to switch on
- a. Electrical fault (most common, usually a fuse, wiring, relay)
- b. Mechanical fault in compressor (rare)
- c. Isolating switch fitted and not turned on (as in a aux. fuse block switch)
2. Compressor fails to switch off
- a. Electrical fault (pressure switch)
- b. Air leak (compressor trying to meet pressure switch req.)
3. Lockers fail to engage when button is presson on
- a. Electrical fault (see part 1)
- b. Sized or leaking solenoid valve (easy to swap, relatively cheap)
- c. Mechanical fault in compressor (rare as mentioned before)
Common Solutions:
1.a & 3.a
- Check the battery terminal is connected
- Check all connections are secure, no loose or disconnected wires
- Check the fuse (system only requires one 30 amp fuse)
- Check pressure switch relay& dash mounted switches
(a simple multimeter/test light can be used for all testing)
1.b
- If mechanical fault is suspected in compressor (return to ARB service center)\
1.c
- Test all functions of isolating block with multimeter/test light
2.a
- Check that pressure switch is functioning using multimeter/test light
2.b
- Air leakage can occur at several locations in the air supply system for a number of reasons.
2.b.1 - Check all connections
2.b.2 - If leak is detected at fittings, remove, clean, apply sealant, and tighten.
3.b
- Solenoid valces (Part# 180102 & 180103) can be disassembled and cleaned.
- Assemble onto compressor using hydraulic sealant (Loctite 569)
- If solenoid continues to fail, replace with nee (tested used) unit
3.c
- If mechanical fault in Air Locker is suspected, remove differential and inspect
