1984 LSC Air Suspension

Hmm,Imagine that. A 20 year old Lincoln with an air suspension problem.
I just picked up this car knowing it had a concern with the right front
dropping at times. It is an 84K well maintained "Grandpas" car.
Here's the story. When I picked up the vehicle, it had been sitting for a week and was at trim height. After about 2 miles the right front corner exhausted completely, no "Check Air Suspension" light.The compressor was not running. I stopped, power cycled the switch in the trunk and the compressor brought the vehicle back to trim and turned off. No problem the rest of the way home. When I got home, the first thing I did was turn off the system and put the car on 4 jackstands to inspect the air springs.The rears are fairly new, verifying what I was told by the previous owner. The front have been replaced sometime in the past. All 4 look good, no cracks or rust in the folds or leaks. I checked them with a soap solution, along with the seals around the air solenoids. I put it back on the ground and ran the self test, no faults were indicated. All 4 corners inflated and exhausted normally, etc.
Did a "Down and dirty system test".I had 2 180lb friends sit on the front of the car, the system brought itself back to trim. When they got off, it exhausted back to trim. I let it sit for 2 hours with no chenge in height. When I drove it around a 3 mile block the right front dropped again. I got home, scratched my head for a few minutes picking my brain and consulting an electrical schematic, which I also found online. When I turned the ignition on, the compressor engaged and brought the vehicle to trim height and turned off. That was 2 hours ago and she's sitting pretty as you please right now. I guess the cure is to just not drive it. Kinda big for a coffee table and too sloped for a work bench though.:)
I know that if there is a leak the compressor will run to compensate until it times out, then cycling the switch in the trunk will initialize the compressor again. This is not what is happening with this one. The previous owner said that when it happened to him, he would cycle the ignition switch to RUN and back, then after a while it would be "OK" usually for the rest of the day.
Personally I suspect a flaky height sensor but I have no way to be certain.
Can anyone offer any suggestions? Am I missing something?
            Thanks, Tom
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Try driving it with the air ride switch turned OFF. If it drops on the RF then, you have a leaking air spring, soapy water test or not. If it doesn't drop with the air ride switch turned OFF (and DRIVING it), I'd suspect a height sensor. Post your story on: http://disc.server.com/Indices/37091.html for a definitive diagnosis.
Ohio Tom wrote:

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Duuhh, I knew I was missing a step. Thanks Sharon. I tried it this afternoon and it stayed right at trim. But there's more. I turned it back on and drove around for about an hour without a hitch. The right front didn't budge.
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That alone tells you it is not a electronic problem. Most likely what is happening is the bag or air circuit to that bag is leaking. The leak drops the corner so the module turns on the compressor, the leak is fast enough that the compressor can not keep up. This causes the compressors overheat switch to trip compressor turns off. Just because you tried a soap solution does not mean you would see any bubbles. I have found over the years that making your own bubble solution is hit or miss. Go to Wal- Mart, or any place that sells every kids favorite toy, bubbles in a jar. It's cheap and always works. While your there go the garden department and buy a small hand spray bottle. That is now you leak tester. Take the air spring off; inflate it so you can test it unfolded off the car, it only takes a few minutes and is so simple it's stupid. That way any leak "sealed" by the fold in the bag will not be "sealed". A nother known leak area is where the air line fits in the solenoid. The air line gets a groove in it where the solenoid locks into it. Cut the air line just above the groove fixes that.

Not likely, if the sensor went open or short the suspension light will display.

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Thanks Tom, I've used kids bubbles in a quart spray bottle for years for not only air but also AC systems. Works good as a tire mounting lube in a pinch. That's the soap solution I was referring to. I drove the car today with the suspension switch off and it held, but when I switched it back on it worked fine driving for about an hour. I pulled the air bag and inflated it fully with shop air. there were no leaks.I put new O rings on the solenoid and trimmed the line when I put it back together. We'll see what happens tomorrow.             Regards, Tom
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