ALL air compressors produce moisture, no matter the size. Bigger air compressors like whats in an auto repair shop or in most shade-tree mechanics garages, fuel air tools, blow sawdust and air up tires. Although the bigger compressors produce more moisture than a smaller one, the bigger compressor with a tank also has a way to easily drain the moisture from the system. Most people don't realize that an automotive air suspension system is just like an air compressor in their garage with one big difference between them. Because of all the low lying air lines and other parts(air springs - air struts) in the vehicle, there is no way to easily drain moisture out of the system.
You've heard automobile air suspension systems have a dryer that absorbs the moisture? That is true, but keep in mind 2 things:
#1) Having a dryer right off the air source is at best only 95% effective. The reason for this is because a rule of thumb when working with pneumatic tools is, to have the dryer or collector a good 6 feet from the source. This is to allow the hot moisture filled air, time to cool where the dryer can collect it. Not allowing it to cool down, makes the whole drying system less effective, because the water vapor will blow right past the dryer. Short term(when the vehicle is new), you'll never have this problem, because the new dryer has collected most of the moisture and not enough moisture has collected in the system to cause problems.
#2) The dealer won't tell you this because they want you to keep buying air suspension parts and to continue to line their pockets later on when your out of warranty, but the dryer used on most air suspension systems, has a lifespan of only 4-5 years. The majority of the time, the dryer pretty much turns into a collection point. In other words, instead of the moisture gel beads inside the dryer collecting, or trapping the incoming moisture, the moisture is now just sitting in the dryer. The moisture then plays a see-saw game of going back & forth from inside the lines & air springs - struts & back to the compressor. Below is a look inside a compressor that was installed on a vehicle with an excessive moisture problem. It was on the vehicle for only 45 days!
The compressor pumps, or forces air into the system, how does the moisture make it back to the compressor?
It makes its way back to the compressor, because most systems are designed to dry out the moisture absorbing gel beads in the dryer. The plan is, by blowing air that's already in the system, back through the dryer & compressor, it will "dry out" the gel beads. Sounds like a good plan right? Well what happened to all that moisture that was built up and sitting in the dryer? That's right, it's now being forced by high air pressure, through the dryer then through the compressor! In essence, giving the compressor a bath. Keep in mind most of these OEM compressors are designed from the factory, to run dry and WILL BE permanently damaged by ANY moisture or fluid ingestion.
What makes an excessive moisture problem worse?
Any air compressor produces moisture, but what happens when a compressor has to run 2-10 times more than it was designed too, because of a leak?
Answer: Its going to produce 2-10 times more moisture than it would normally. In other words, even if you spend $400-$900(not including labor) for a replacement compressor, the moisture that has built up in the system all those years, will quickly attack & overwhelm the new dryer and in time, damage the replacement compressor. This is why certain air suspension parts have to be replaced more than once.
How long the replacement lasts greatly depends on 2 things:
#1) How much the compressor has to run = If the leaks in the system were repaired.
If the leaks were repaired, you may have a chance. If the leaks weren't repaired correctly, that same 40% duty cycle compressor that's made to run 2-10 times more than it was designed, will continue to run constantly until the small plastic parts inside them melt. Running constantly is also hard on bearings and even armatures, due to the increased amperage draw from swollen(from moisture) parts(piston rings) inside.
#2) How much moisture was in the system. Over the years, we've experienced new $500+ factory air suspension compressors severely damaged, in less than 1 months use. This was due to excessive moisture in the system alone.
One reason air suspension leak down problems seem to get worse when it gets cold, is because the "rolling lobe" type air bladders are starting to show their age. Due to dry rot, the rubber air bladder will develop small cracks on the fold(where the rubber folds around on the bottom). When temperatures drop, the older, dried out area of the air bladder will get hard and won't be able to seal itself.
The air suspension system doesn't produce much moisture in colder weather, but the moisture that has collected in the system during the warmer months, can & will hurt system performance. When the moisture that is laying in the dryer drops below freezing, the dryer can easily become a solid block of ice. When this happens, it can be really hard for air to travel in any direction. This means no load leveling when weight is added, but also no venting the air after the weight is removed. Say you were lucky enough to have the compressor squeeze enough air pressure past the solid block of ice in your 10+ year old dryer. You take your car and drop someone off. NOW, the system can't relieve all the extra air in the system because the air can't get past the ice.....and you drive around looking like a 4x4!
With all this being said, ANY business selling air suspension parts would make way more money if you stayed with the air, as you will continually buy parts for your car. Our recommendation would be to remedy those air suspension problems forever with a Air Suspension Conversion Kit for 2000-2006 BMW X5
or Air Suspension Conversion Kit for 2007-2012 BMW X5. Its a simple, straight forward repair and is the ONLY way that you'll be able to rely on this vehicle!