98 PA air struts

The rear air struts are fully extended, the rear end is up in the air. It started after the last Buick Dealer wheel alignment.
Can I deflate the struts by disconnecting the air lines from the pump? The pump seems to run as little as it always has. Is the strut level controlled by the computer? Could the little control arm box on the left rear axle be defective?
Right now the rear end wants to jump sideways when hitting bumps on the freeway.
I am dealer shy!
Joachim Sr.

You have a level switch with a rod, between the switch and the body. It could just need adjusting, could be loose, or a bad switch. You can pull the fuse for the ALC and open an air line to deflate if you want to.

Thank you for replying. I have removed the pump with the attached filter and one-way valve. The struts have deflated to where they should be in the first place. The level switch on the left rear trailing arm is operational and adjusted. The dealer says that the struts should deflate after the key has been removed from the ignition. I don't know how that can be since the one-way valve in the filter assy. will prevent such deflation.
Joachim Sr.

The struts should not deflate when you turn off the ignition!! Are you planning to run the struts without air? That would be a bad idea, since they are designed to have some air assist in the bladders for proper ride control.

Thank you again for replying. I have reinstalled the pump and filter after checking it out and cleaning it. This only verifies my position that not all dealer "specialists" know operational parameters of the equipment they sell or service.
I will again check the interior of the level switch for anomalies and readjust if necessary.
Thank you, Joachim Sr.

Well, I tried to take the switch out but it has about eight wires into it and the cabling goes through the frame in such a way that I have reconsidered my motive.
Maybe that is not the air strut pump switch. It is mounted on the left rear frame with a ball-end rod going to the axle swing arm. How is it adjusted?
The arm is solid, no threads or nuts.
Maybe after a while I just have to disconnect the two airlines and bleed the struts. The dealers certainly don't know how to do that.
Thanks, Joachim Sr.

After you let the air out, are the struts still inflating to the full extended position everytime? The switch you found with the rod to the lower control arm is the right one. Some have an adjustable rod, but it sounds like yours is not adjustable. Can you move the switch or rod mount to adjust? Your switch may be stuck in the on position and you are pumping air until the compressor times out. (5-min) Check to see how long the compressor runs when the struts are deflated, (with lines hooked back up) before it turns off. You can always install a manual fill system to eliminate the ALC if you want. That is what I did. You can get the kit at Advanced of O'Reilly auto parts, (Monroe part #AK29)
Auto Parts and Auto Accessories at Advance Auto Parts (http://www.partsamerica.com/)
O'Reilly Auto Parts - Professional Parts People (http://www.oreillyauto.com/B2C/vehicle.ecatalog)

Neither switch nor rod can be moved. The pump usually only runs for a few seconds at a time. Since I have reassembled the pump, repaired the broken wire, the top of the fender stays at a steady 28.25 inches. I will just have to see what the future will bring. Let's say that I go on a trip with the trunk and rear seat loaded to max. The pump loads the struts to keep the car level. After the trip the car is empty the struts fully loaded. How are they supposed to discharge air to bring the car down again? Is there a mod which opens the airlines and bleeds the struts? Taking the connection loose at the pump filter is not a desired thing.
Thanks, Joachim Sr

Basically, this is how the system works;

System activates when ignition is turned on, and remains active 6 min, after switching ignition off.

Compressor head houses the dump valve. There is an 8-15 second delay in the sensor circuit, to prevent compressor or dump valve operation during normal driving.
.
Sensor also limits compressor run time-dump valve cycle to 6 min, incase of severe system leak; turning ignition on & off resets the run time. This is known to cause the fuse to blow, or the compressor to fail. (Too many cycles in a short period of time)

An air replenishment cycle is initiated when the ignition is turned on. If the vehicle is a the correct height, a timer starts and after 35-40 seconds, the compressor will run for about 4 seconds to ensure that the shocks are filled with adequate residual pressure.(8-14 psi)

If weight is added to the vehicle during the replenishment cycle, the replenishment is over ridden.

To reduce compressor starting current, the dump valve is opened for 1.5 sec. each time the compressor starts.

After turning on the ignition and allowing the replenishment cycle to complete, add 300 pounds (1,2 or 3 friends depending on size) to the trunk area and observe the drop in ride height. After 8-15 seconds you should hear the compressor start (listen closely by the front left fender and you will even hear the 1.5 second dump valve operation). Then with the 300 pounds still in the trunk area, observe the body trim moving up to the correct ride height. The compressor will then cut off, and your car will stay at the correct height.


Remove the load (car will rise too high) and listen again near the compressor, after 8-15 seconds, you should hear air escaping through the dump valve.

Dear HOTZ28,
Thank you very much for all the info. Everything seems to be working alright now when it comes to the car's rear end height and compressor operation.
However, the car still wants to jump sideways when one or the other rearwheel hits a bump in the road. It is not too noticable when both wheels hit the bump at the same time. This started right after the car was 4 wheel aligned by the Buick Dealer in Peoria, AZ. At the time the rear end was sitting at max height and it was not lowered by the dealer before commencing alignment. Could that have caused improper alignment?
JAG

Dear HOTZ28,
At the time the rear end was sitting at max height and it was not lowered by the dealer before commencing alignment. Could that have caused improper alignment?
JAG:uhoh:

Yes, the caster & camber can be affected by the body height. Most alignment “professionals” want the car at the proper ride height when setting the alignment. Some will even ask the driver to remain in the car to simulate the normal ride height, with driver weight on board. That is how critical it is, especially with 4-wheel alignment!


Caster:
Caster is the tilting of the uppermost point of the steering axis either forward or backward (when viewed from the side of the vehicle). A backward tilt is positive (+) and a forward tilt is negative (-). Caster is affected by the vehicle height, therefore it is important to keep the body at its designed height. Overloading the vehicle or a weak or sagging rear spring will affect caster.
When the rear of the vehicle is lower than its designated ride height, the front suspension moves to a more positive caster. If the rear of the vehicle is higher than its designated trim height, the front suspension moves to a less positive caster. With too little positive caster, steering may be touchy at high speed and wheel returnability may be diminished when coming out of a turn. If one wheel has more positive caster than the other, that wheel will pull toward the center of the vehicle. This condition will cause the vehicle to pull or lead to the side with the least amount of positive caster.

Camber:
Camber is the tilting of the wheels from the vertical when viewed from the front of the vehicle. When the wheels tilt outward at the top, the camber is positive (+). When the wheel tilts inward at the top, the camber is negative (-). The amount of tilt is measured in degrees from the vertical. Camber settings influence the directional control and the tire wear.
Too much positive camber will result in premature wear on the outside of the tire and cause excessive wear on the suspension parts.
Too much negative camber will result in premature wear on the inside of the tire and cause excessive wear on the suspension parts.
Unequal side-to-side camber of 1° or more will cause the vehicle to pull or lead to the side with the most positive camber.