Thread: D3 air compressor

1--Mounting bracket
2 -Air dryer
3 -Pilot exhaust valve solenoid and temperature sensors harness connector
4 -Motor harness connector
5 -Intake port
6 -Pilot exhaust valve
7 -Exhaust valve
8 -Isolation mounting rubber (2 off)
9 -Electric motor
10 -Isolation mounting rubber (1 off)
11 -Pilot air pipe
12 -High pressure supply to air suspension system
13 -Compressor cylinder head temperature sensor
14 -Compressor

Pilot Exhaust Valve

A solenoid operated pilot exhaust valve is connected to the air delivery gallery, downstream of the air dryer. The pilot valve, when opened, operates the main compressor exhaust valve. This allows the air springs to be deflated when required.

When the solenoid is energized, pilot air moves the exhaust valve plunger, allowing pressurized air from the air springs and/or reservoir to pass via the reservoir control valve to the air supply unit.

The solenoid has a resistance value of 4 Ohms at a temperature of 20°C (68°F).


Exhaust Valve

The exhaust valve has three functions. It operates in conjunction with the pilot exhaust valve to allow air to be exhausted from the air springs and/or the reservoir as described previously.

The valve also protects the system from over-pressure. The valve is connected into the main pressure gallery which is always subject to the system pressure available in either the air springs or the reservoir. The valve is controlled by a spring which restricts the maximum operating pressure to between 333.5 to 370 lbf/in2 (23.0 to 25.5 bar).

The minimum pressure in the system is also controlled by the exhaust valve to ensure that, even when deflated, the air springs contain a positive pressure of approximately 14.5 lbf/in2 (1 bar gage) with respect to atmosphere. This protects the air spring by ensuring it can still 'roll' over the piston without creasing.


Electric Motor

The electric motor is a 12V dc motor with a nominal operating voltage of 13.5V. The motor drives a crank which has an eccentric pin to which the compressor connecting rod is attached.

The motor is fitted with a temperature sensor on the brush PCB assembly. The sensor is connected to the air suspension control module which monitors the temperature and can suspend motor operation if an overheat condition occurs.


Compressor

The compressor comprises a motor driven connecting rod and piston which operate in a cylinder with a cylinder head. The motor rotates the crank moving the piston up and down in the cylinder bore. The air in the cylinder is compressed with the up stroke and is passed via delivery valve, through the air dryer into the system.


Air Dryer

The air dryer is an integral part of the air supply unit. The air dryer contains a desiccant which absorbs moisture. Pressurized air is passed through the air dryer which removes any moisture in the compressed air before it is passed to the reservoir and/or the system

When the air is exhausted from the system, the returning air is passed through the air dryer, regenerating the air dryer by removing moisture from the desiccant and expelling it to atmosphere via the exhaust.

The air dryer is an essential component in the system ensuring that only dry air is present in the system. If moist air is present in the system, freezing can occur, resulting in poor system operation or component malfunction/failure.

(Source: Land Rover Global Technical Reference)

Good man, i was just reading some of your posts on the D3 forum and was hoping you might see my post.

thanks,
Nick.

I am going to mount this compressor in my disco and also have an expired small fire ext that i could use as a reservoir, anyone used one of these and where should i empty the contents ?

Also check the part number. I think it's on the end of the motor unit.

If it's RQG500065, then the compressor may fail.

If it's RQG500072, then it may need a new exhaust valve.

If it's RQG500090 or higher, then it should be fine!

Originally Posted by Jamo

Also check the part number. I think it's on the end of the motor unit.

If it's RQG500065, then the compressor may fail.

If it's RQG500072, then it may need a new exhaust valve.

If it's RQG500090 or higher, then it should be fine!

I will check it out, from what i've heard it was only the wiring loom of the compressor that actually failed ? Exhaust wont be used as its only to deflate the airbags which i dont have and it will only be used occasionally anyway.

Nah, I had the 60 model as originally fitted and the compressor itself gave up the ghost completely. These were replaced in all cars as part of the 'enhancement'. If the exhaust valve's not a problem, then the 72 will be fine.

I don't exactly know what failed within the 60, but I think wiring loom problems were a separate issue.