HOW DO I FIND PROBLEM FOR REAR LEVELING AFTER INSTALLING AIR SHOCKS AND I CAN HEAR AIR COMPRESSOR PUMP COME ON.

You need to check a few things. Do you ever hear the air compressor at the rear of the vehicle running?
If so, does it run continuously with the ignition on? (that will mean there is usually an air leak either in one of the rear shocks or the air lines/connectors).
If not, either the compressor, or the compressor relay, level switch and/or the fuse may be shot and each will have to be checked.

Yes to much of this.

Compressor is close to the shocks - Start with electrics - Find wiring and check for voltage at the compressor - compressor is small like the little ones you buy for tire pumping - like small -

Jumper a temporary wire from battery to compressor does that work? If not just replace the compressor. I've replaced mine twice for corrosion issues.

If pump works, look for leaks or leaking shock. You can use a tire pump to check shocks leaking.

this happened 2 me also because the rear air shocks were popped, they are very expensive 2 replace with factory parts, I found aftermarket air shocks for $80 but you need 2 fill them manually and disconnect the compressor . If you want 2 track the lines the compressor is behind the front bumper near the passenger side wheel well from there you can follow the lines 2 the shocks, meanwhile you should disconnect the air compressor it can burn out from running all the time. The factory shocks are close 2 $300 ea. with the aftermarket shocks there with be a valve stem 4 you 2 fill them with and are easy for a do it yourselfer

The air pump for the secondary air system (emission control device) is located under the battery. If you do replace it, replace the check valve too, it is on top of the exhaust manifold and connected to the pump with a hose. The check valve fails and ruins the pump. Source(s): http://repairpal.com/volvo-850-1997/comm…
http://repairpal.com/air-pump-check-valv…
http://repairpal.com/air-pump

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I think they are talking about the pump to provide vacuum to the climate control when the turbo is putting boost in the intake manifold. The vacuum can come from an electric pump or from an engine driven pump, something like an old engine driven fuel pump. I needed an electric pump for my 765T, and all the wrecking yards wanted to sell me the engine driven form. (A new one was $500, and it wasn't that important to me.)

An engine that takes the engine driven pump will have a hole in it while the others will not have a hole. Source(s): 35 years maintaining my own cars, including 17 years with a 1985 765T


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Rear Suspension Leveling Air Compressor
RH front of vehicle, attached beneath the fascia

Rear Suspension Leveling Air Compressor Relay K19
Lower I/P, to the RH side of the steering column, on the relay box


Automatic Level Control System Operation Check
Support the rear wheels or support the rear lower control arms when certain tests require raising the vehicle on a hoist. Use two additional jack stands in order to support the rear lower control arms in the normal curb weight position when a frame type hoist is used. Refer to Trim Height Specifications in Suspension General Diagnosis.

Refer to ALC Suspension System Check for electrical troubleshooting of the Automatic Level Control (ALC) system, or if DTC's are present.

Diagnosing Leveling Complaints Without DTCs Present Procedure
Perform the following preliminary inspections before performing the system performance test:

Inspect the ignition (pin A & pin H) at the ALC sensor connector.
Ensure that the ignition (pin A & pin H) at the ALC sensor connector connection is secure.
Inspect the ground (pin E) at the ALC sensor connector.
Ensure that the ground (pin E) at the ALC sensor connector connection is secure.
Inspect the ALC sensor link.
Ensure that the ALC sensor link is properly secured to the actuator arm.
Inspect the ALC sensor actuator arm for damage.
ALC Diagnosis Table Step
Action
Value(s)
Yes
No

1
Has the ALC compressor assembly and the air tube been replaced?
--
Go to Step 7
Go to Step 2

2
Raise and support the vehicle. Lifting and Jacking the Vehicle in General Information.
Inspect the air tubes running from the ALC compressor to both rear shock absorbers.
Inspect the air tube connection at the ALC air dryer.
Are the air tubes damaged and/or disconnected?
--
Go to Step 13
Go to Step 3

3
Squeeze the left rear shock absorber in the middle of the air sleeve.

Did the air sleeve slightly compress?
--
Go to Step 5
Go to Step 4

4
Operate the ALC system for 60 seconds.
Test the air tube-to-air dryer connection for leaks using a soap bubble solution.
Is a leak evident?
--
Go to Step 20
Go to Step 5

5
Disconnect the air tube from the ALC dryer.
Connect the Pressure Gauge to the ALC dryer.
Close the toggle valve on the Pressure Gauge .
Operate the ALC compressor.
Did the pressure build to the specified value?
80 psi
Go to Step 6
Go to Step 10

6
Shut off the compressor when the pressure reaches 80 psi.
Monitor the gauge for 1 minute.
Did the pressure leak down?
--
Go to Step 10
Go to Step 7

7
Connect the Pressure Gauge to the right rear shock absorber. Ensure that the toggle valve on the Pressure Gauge is away from the shock absorber.
Close the toggle valve.
Pressurize the shock absorber at the toggle valve on the Pressure Gauge to 80 psi.
Monitor the gauge for 1 minute.
Did the system leak down?
--
Go to Step 11
Go to Step 8

8
Use the toggle valve on the Pressure Gauge in order to slowly release the air pressure.
Disconnect the Pressure Gauge from the right rear shock absorber.
Connect the Pressure Gauge to the left rear shock absorber.
Pressurize the Pressure Gauge to 80 psi.
Monitor the gauge for 1 minute.
Did the pressure leak down?
--
Go to Step 12
Go to Step 9

9
Use the toggle valve on the Pressure Gauge in order to slowly release the air pressure.
Disconnect the Pressure Gauge from the left rear shock absorber.
Connect the Pressure Gauge , inline, at the tee near the rear of the vehicle.
Reconnect the air tube to the ALC dryer.
Open the toggle valve on thePressure Gauge .
Using shop air, pressurize the system to 80 psi at the service connection of the Pressure Gauge .
Monitor the pressure gauge for 1 minute.
Did the pressure leak down?
--
Go to Step 14
Go to Step 20

10
Replace the following components:

• Replace the ALC compressor. Refer to Air Compressor Replacement .

• Replace the air tube. Refer to Air Tube Replacement .

Are the replacements complete?
--
Go to Step 20
--

11
Slowly open the toggle valve on the Pressure Gauge in order to relieve the air pressure.
Replace the right rear shock absorber. Refer to Shock Absorber Replacement in Rear Suspension.
Reconnect all of the air tube connections.
Is the shock absorber replaced, and are all of the air tube connections reconnected?
--
Go to Step 20
--

12
Slowly open the toggle valve on the Pressure Gauge in order to relieve the air pressure.
Replace the left rear shock absorber. Refer to Shock Absorber Replacement in Rear Suspension.
Reconnect all of the air tube connections.
Is the shock absorber replaced, and are all of the air tube connections reconnected?
--
Go to Step 20
--

13
Are any of the air tubes damaged?
--
Go to Step 14
Go to Step 18

14
Replace the air tube that runs from the air dryer to the two rear shock absorbers.

Is the replacement complete?
--
Go to Step 15
--

15
Remove the ALC air dryer from the compressor assembly.
Shake the ALC air dryer with the head connection down.
Did water/moisture come out of the ALC air dryer when the dryer was shaken?
--
Go to Step 16
Go to Step 17

16
Replace the ALC air dryer. Refer to Automatic Level Control Air Dryer Replacement .

Is the replacement complete?
--
Go to Step 17
--

17
Replace the air compressor head. Refer to Automatic Level Control Air Compressor Head Replacement .

Is the replacement complete?
--
Go to Step 18
--

18
Install the ALC compressor on the vehicle.
Reconnect all of the air tube connections.
Is the ALC compressor reinstalled, and are all of the air tube connections reconnected?
--
Go to Step 20
--

19
Repair the air tube-to-air dryer connection leak.

Is the repair complete?
--
Go to Step 20
--

20
Reconnect all of the connectors that were disconnected.
Reconnect all of the components that were removed.
Clear all of the codes with the ignition ON and with the engine OFF.
Wait at least 5 minutes.
Is the rear of the vehicle trim level?
--
System OK
--

Check the electrics and sensors to the pump

To begin with, check the "ride level" fuse and make sure that the ride level compressor does work, and you should be able to hear that the ride level compressor is working when the ride level system is leveling the vehicle.

The ride level system uses an air compressor and either an air type of shocks or a type of air billow to raise and lower the vehicle, there is an adjustment to set the ride height and it is located under the vehicle and there is a control lever or rod that should be connected between the rear axle and a switch that is mounted on the body of the vehicle, and there will be an adjustment slot in the control lever between the switch and the body, and that is how you would adjust the ride level height, but be sure that the vehicle can not drop any further down if someone is under the vehicle trying to adjust the ride height.

However, you might find that the control lever to the ride level has fallen off from the switch on the body or it has come loose from the rear axle, and it is just hanging there not operating the switch on the body that controls the the ride level compressor, or there might be a blown out air shock or billow, or you might find that an air line from the compressor is leaking and the ride level compressor will just run continuously until it blows out the fuse, and if that is the case you might also find out that the air compressor has burned out from running continuously.

I hope that this information will help you to solve your ride level problem.

To begin with, check the "ride level" fuse and make sure that the ride level compressor does work, and you should be able to hear that the ride level compressor is working when the ride level system is leveling the vehicle.

The ride level system uses an air compressor and either an air type of shocks or a type of air billow to raise and lower the vehicle, there is an adjustment to set the ride height and it is located under the vehicle and there is a control lever or rod that should be connected between the rear axle and a switch that is mounted on the body of the vehicle, and there will be an adjustment slot in the control lever between the switch and the body, and that is how you would adjust the ride level height, but be sure that the vehicle can not drop any further down if someone is under the vehicle trying to adjust the ride height.

However, you might find that the control lever to the ride level has fallen off from the switch on the body or it has come loose from the rear axle, and it is just hanging there not operating the switch on the body that controls the the ride level compressor, or there might be a blown out air shock or billow, or you might find that an air line from the compressor is leaking and the ride level compressor will just run continuously until it blows out the fuse, and if that is the case you might also find out that the air compressor has burned out from running continuously.

I have a 2001 Expedition, I don't have air bags in the front, the compressor don't work the air shocks. You have rear leveling. When they replaced the (compressor) did they turn the leveling switch back on. you may have air shocks connected to the compressor. Did the rear go down right after or over a couple of days. If the switch is on, turn it off and jack the rear up quiet a bit, make sure both side are quiet equal with each other, like it would be if it where raised by the air bags. Turn your level switch back on with it jacked up or sitting on stands. It may have went down so much that the compressor can't raise them back up.

The problem is a leaking air shock(s). My 1997 catera had this problem also. I drove the rear wheels up on a set of ramps and went underneath. There is a sensor located close to the rear axle's that moves up when the car is loaded in the rear. (luggage/person in the back seat). When the car senses the extra weight, a small compressor located up under the hood pumps air to the air shocks until the car is back level again. With the key turned on, and the engine off, You can actually move this sensor with your hand and after about 45 seconds, you will hear the small electric compressor come on and see the rear of the car rise. Even if the shock is leaking, the car will still rise but you can hear/feel the air leak on the rubber boot of the shock. The reason the light never stops flashing is because of the air leak the car never really reaches proper leveling. I know what your thinking, "I didn't have extra weight in the car"..doesn't matter car still levels itself from time to time without extra load in the rear. Possible road conditions etc. and also the fact your basically riding around with only one rear shock working like it should. hope this helps......dave

Can you hear the pump kick in when you put weight in the back and the car is running? The way it works is there is a level sensor that mounts between the body of the car and the rear axle. When weight is added in the rear the compressor will add air until the vehicle is level. When weight is taken out of the car which could be the rear passengers getting out of the car the vehicle is now higher and the pump will release air to lower the shocks back to a level height. This is why youare hearing that sound. The pump will let air out of the system even when the engine is off to maintain a level ride. If you found this solution helpful please rate it.

Thanks - Tech101