FAQ: Automatic Leveling Control (ALC) Concerns

Just an FYI to anyone who has a non-functional ALC. Check the vacuum lines that go to the 2 modules next to the compressor. There are 3 nuts that hold the bracket holding the compressor/2 units to the car. After that it just kind of slips out and drops down, and at this point you can remove it if you need to or check on these lines. Mine were so rotted they just fell apart in my hands. They weren't even connected because they had just rotted off of the 2 nipples they attached to.

matt270avian wrote:

Just an FYI to anyone who has a non-functional ALC. Check the vacuum lines that go to the 2 modules next to the compressor. There are 3 nuts that hold the bracket holding the compressor/2 units to the car. After that it just kind of slips out and drops down, and at this point you can remove it if you need to or check on these lines. Mine were so rotted they just fell apart in my hands. They weren't even connected because they had just rotted off of the 2 nipples they attached to.

I had the same problem with mine. No more leaks once I replaced them.

Update:  My compressor problem is still with me.  It runs for a shade under 5 minutes and cuts off.  Fine.  Has to be either a compressor or a rubber line.  The car rides over bumps MUCH better and is rock solid to the bounce test.  In the rear.  Fronts?  Next thing that needs changing.

Anyway, the compressor.  Was in the junkyard a couple of days ago and decided to snatch a compressor unit because...why the heck not.  $45 bucks.  New they went for like $500.  Anyway, remove the plastic splash panel (3 Philips screws).  Then disconnect a black "pinch" clamp arrangement that disconnects both air lines to the shocks from the compressor.  This is rigid thin plastic, similar to what the vacuum lines are under the hood.  Next disconnect a large electrical connector mounted to the fender well by removing a little white spike-type retainer, then get a pick, and disconnect by wiggling.  Then remove a 10 mm bolt that attaches one of the rigid lines AND the front of a metal plate that reminds me of a skid plate you'd see under a car to protect oil pans.  Easy peasy, vertical mount comes off 1-2-3.  Next, get on your back, move to the rear of the car right next to the muffler and you'll see 2-10 mm bolts on the back of the skid plate oriented horizontally.  They come off easy.  Remove the skid plate and you can leave or disconnect another electrical connector.  That connector is what powers the compressor.  You can leave it on the skid plate if you're taking it from the junkyard or just pry it off with a "V" shaped trim removal tool or a screwdriver.  You then disconnect a long, about 14" long rubber vacuum line from a green nipple mounted on the inner fender. Net, remove 3 bolts with attached rubber insulators, and the compressor unit drop down easily.  When I dropped the unit, the first things I said was "holy sh*t, these rubber hoses are shot".  Yep, original GM 7/32" hose.  There are 3 of them.  Long one is about 14-15" and mounts to the aforementioned fender well nipple, medium is about 6-7" and the short one is about 5".  Both of these mount to the compressor/dryer (maybe that's the correct term--anyway, these have metal, not plastic nipples. All three of these lines connect into a plastic "T" fitting.  So home I go, and decided to do mine.  Lo and behold, I find my lines are cracked and one of the lines separated to the touch.  Figger, why not try and replace the lines first.  So my local auto parts store sell 7/32" hose, blister packed, 6' long for less than $4 bucks and is cheaper than hose "by-the-foot".  The brand was Prestone, like the antifreeze.  Came home, had the car jacked up, skid plate removed, and I was able to change all three hoses without dropping the compressor.  TIP:  2 things to do if you're changing hoses.  Clean the nipples and squirt some silicone spray on them.  7/32 is a tight, TIGHT fit.  No clamps necessary.  And put the hoses FIRST on the nipples on the compressor unit and fender well nipple BEFORE you hook it all up the "T" fitting.  Much easier manipulating the hoses if you do it in that order.  Buttoned it all up and no more compressor noise.  If you get a hint of your compressor running too long, change this out before you're relying on some sort of thermal overheating safety switch to stop the compressor.  $4 bucks is cheap insurance and the job takes about an hour.  Good luck. Oh, while I'm a firm believer thinking that smarter people who get paid 6 figure salaries as engineers designed this for 7/32", I'd not be surprised if 1/4" or 8/32" hose works just as good, would stay in place, and be a darned sight easier to install. But since I already bought it, figured I stick with the 7/32".