How To Diagnose and Fix Hummer Air Ride Suspension Components: Suspension Compressor, Air Suspension/Shocks, Coil Spring Conversion Kit

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Vehicles Affected:  2003-2009 Hummer H2 w/ Rear Air Suspension System

Tools Needed: Basic Hand Tools

Parts Needed: Air Suspension To Coil Spring Conversion Kit or Air Suspension Bags/Compressor & Components

Problem: The 2003-2009 Hummer H2 had an option from the factory to get a standard coil spring suspension or an air ride suspension. The air ride suspension is an awesome feature to have when it is brand new, however, over time the system can need repairs that can easily add up into the thousands of dollars. The vehicle owner really needs to know all of the possible costs involved with the normal & continuous degradation of an air suspension system. The air ride suspension consists of these parts:

Air Suspension Compressor/Dryer/Valve Body Assembly

Air Suspension Control Module (also called Air suspension brain or computer)

Air Suspension Air Bags/Springs (the proper term is air spring)

Air Ride Height Sensors/Air Ride Control Relays/Ride Height Switch – Not Available In The Aftermarket At The Time Of This Article, Consult Your Hummer/GM dealers for pricing (Order by your VIN)

The purpose of the air suspension components are to keep the vehicle visually level & to maintain a proper ride height when the vehicle is loaded or unloaded. This maintains the alignment and prevents premature tire wear. Note: Many Hummer owners switch the OE wheels to oversize wheels such as 24″ wheels, This can change the geometry of the vehicle alignment and can result in un-even tire wear.

Fergies Hummer H2

Fergie's Hummer H2 With 24 Inch Wheels & AIr Suspension

Here is a picture of Fergie’s Hummer H2 that she sold on eBay, Fergie we love you and please let us use your picture without any money as we are poor poor poor and eventually your air ride will need some repairs.

So here is what you want to read if you are deciding to convert it to a standard coil spring suspension or repair the air ride suspension. First of all, if you are reading this then most likely the rear end of your hummer is sagging or it is at the dealer and you just got the estimate to repair it. In either case the air ride suspension usually starts out with a leaking air spring or a burned out compressor. A leaking air spring is not a big deal, however consider this: Once your air bag starts leaking, it makes the air suspension compressor run longer and come on more often then it was designed for. This will shorten the life of the air suspension compressor and the absolute worst thing that can happen is you pay $200-$300 to replace one of the air springs, If you replace both air springs, then you are probably around $500. The shop calls and says it is done, you go to pick it up and see the rear-end is back up like it is suppose to, you are happy, you pay, and you leave. Everything is fine and dandy for a few months and then all of a sudden you come out to find the rear-end sagging again. You take it back to the shop thinking and hoping a small problem happened and they will get it fixed up for you and it might not cost you anything. Then you get the dreaded phone call that you air suspension compressor is burned out. The next sentence is the compressor is $2500.00 and the labor is, blah, blah, blah. At this point you are caught off guard and puzzled over the insane cost to fix this. You are thinking why did the shop not see this 3 or 5 or 8 months ago when they replaced my air springs. Well the simple answer is they cannot tell unless they take apart the compressor and do an internal inspection and unless you are willing to pay the labor to do this, well it just is not getting done. Also most shops are trained to repair the vehicle back to OE original design so they are doing what they are suppose to do and probably will not even offer the conversion kit unless you bring it up. This is why the vehicle owner should fully understand the entire system before deciding how to repair it.

So you have 2 options, 1. Spend lots of money and repair the air suspension, or

2. Convert the darn thing over to a very easy, very in-expensive, MADE IN THE USA, conversion kit that many people can install themselves if you so dare.

Here are instructions for both, Starting with the conversion kit that we strongly recommend:

CONVERSION KIT INSTALLATION INSTRUCTIONS:

1. Raise and support the vehicle properly and safely according to a GM repair manual or owners manual (We have to say it like that so in-case you drop the car off of the lift, we are not liable, we are just trying to help you)

2. Remove the rear wheels from the vehicle and set aside

3. Look at the center of the rear axle and you will see the air suspension compressor assembly behind it. It will look like the image below:    Note: The image below is a dual compressor assembly found on 2005-2007 H2 models, If you have a 2003-2004 H2, you may have the older single compressor, Read our repair instructions farther down this post for more info on the different compressors.

Actual Image Of A Brand New Air Suspension Dual Compressor Assembly

4. Remove the compressor assembly form the vehicle. First remove the air lines. If you have a proper scan tool, you can use it to depressurize the bags, If you do not, then use caution with the next step. Do not let the air shoot right into your face to avoid hurting yourself. These are quick disconnects and all you do is push in on the line until the fitting goes in, then pull the line itself out of the fitting while keeping the fitting pressed in. Play with it a few times and you will see how it works, these come right out and if done properly, very little force is needed. Then disconnect the control module or brain, this is a large plastic connector that simply unplugs, some models will have a small clip keeping the connector attached. Once you have the wiring and air lines disconnected, next unbolt the assembly form the vehicle and set aside. You will not be putting the compressor back into the vehicle if you are converting it. Also by unplugging the compressor control module, you are de-activating the suspension light on the dashboard.

5. Now go to the air springs and disconnect the air lines form the springs/bags using the same quick disconnect procedure above (push in on the fitting and then pull the line out)

6. It is safest to lower the vehicle down until the rear axle tube is about a foot off of the ground (The front wheels are still bolted to the vehicle, so if you lower it until the front wheels almost touch the ground and use a floor jack to jack up the rear axle tube to take the load off of the shock absorbers. Then unbolt the bottom bolt from the shock absorbers and slide the shocks away from the rear axle. The air springs/bags are held into place by simple clips and the shock absorber keeps the air spring from extending out too much as it can only extend out as far as the shock extends.

7. Time to remove the air springs/bags form the vehicle. The air bags are snapped into place at the bottom and the top is a turn & lock clip design. Look closely at the top of the air spring and you can see the clip, The air bags should be empty now since you disconnected the airlines. You can push down on the top clip and grab the bladder of the air spring and try and turn it by hand. These are not bolted in and you have to turn the air spring to unlock it form the clip. To release it, simply rotate the top and pull down. Here is a sketched image exploded view of the air spring:

Exploded View Of The Air Spring Bag On Hummer H2

8. The bottom of the air bag is snapped into place also, You can use a long flat head screw driver to pop it off of the clip. Remove the air springs and do what you want with them, they will not be re-used.

9. Time to install the nice new reliable and low cost steel coil springs. We are also proud to say these are manufactured right here in the USA, that is a rare thing and we strongly promote any US manufactured products. OK, Take the coil springs out of the box and look at them closely. They will have a label on them for left or right. Left is the driver side of the vehicle and right is the passenger side. Install the coil springs with the tighter wound coils on the bottom or in other words the end where the coils are closer together. (The manufacturer has changed the design on these springs a few times, look at the instructions included with the springs if it is confusing. One of the designs is both springs are identical and others their is a left & right. The kits we have at the time of writing this article came directly from General Motors and their is a right and a left.)

Exploded View Of Coil Spring Installed In Place Of The Air Spring Bag

10. With the shocks still unbolted, fit one side of the coil spring into place. You will see the spring sits onto a pre-made mount for the bottom that is exactly where the air spring was located, the top of the spring also fits into a spring seat. You will need to jack up the floor jack to get the spring to stay into place, At this point you can slide the shock bolt back into place to hold the coil spring in place. YES THIS IS DESIGNED THIS WAY BY GM AND IS PERFECTLY NORMAL. Their is nothing holding the spring into place except the spring seats and the shock absorber being bolted into place. DO this same process for the other spring and once you have the shock bolts into place and make sure the springs are seated properly, then tighten up the shock bolt & nut to 70 ft/lbs.

11. Re-install the wheels and safely remove the vehicle from the lift. Take it on a test drive and feel your new suspension. NOTE: It can take several days to weeks for the springs to finally settle. If you are planning to align the vehicle for normal maintenance, then wait until the springs have settled to avoid a faulty alignment. It is always a good idea to have an alignment checked after any major suspension work.

SUSPENSION COMPRESSOR/CONTROL MODULE/AIR SPRING INSTRUCTIONS

A thorough visual inspection & diagnosis is the absolute first thing that should be done when attempting to fix the air suspension system. Inspecting the system is done to access the overall condition of all the components. Many times an air bag is failed and the dealer or shop says ok its only $300-$400 to fix, you replace the leaking air spring and a few months later the compressor burns out, now it is $2500 to put in a new compressor. The vehicle owner must completely understand all the possible costs involved with a full and long-term proper repair. This is where many Hummer H2 owners decide to convert the suspension to a standard coil spring suspension. If you proceed with repairing the air ride, here is a summary of the instructions, Diagnosing the system is left out as that is very lengthy and would easily be 5-10 pages worth of typing. Also diagnosing this system is not really something a do-it-yourself-er can or should be doing as a bi-directional scan tool, proper DVOM (Digital Volt/Ohm Meter), & wiring schematics are really needed.

1. Identify the type of compressor you have, Typically if you have a 2003-2004 H2, then you probably have a single compressor assembly mounted behind the rear axle. If you have a 2005 -2007 H2, then you have a dual compressor assembly mounted behind the rear axle. If you have a 2008-2011 H2, then you also have a dual compressor mounted behind the rear axle, however it is a different part number then the 2005-2007 models.

2. Now that you know which compressor you have, you can start to figure out what to buy to replace it, General Motors discontinued the single compressor and now requires the 2003-2004 models to be upgraded to the dual compressor setup when a replacement is needed. GM introduced an airline kit that is needed to upgrade the single compressor to the dual compressor. If you need technical support figuring out how which compressor you need, you can call our tech support number at 1-866-770-2771. For all the 2003-2011 models, GM now only offers the complete Dual Compressor assembly. So if you have a single compressor from the 2003-2004 models, you will also need to buy the air line kit. Also assuming you have properly diagnosed the vehicle, you need to consider replacing the control module if it does not come with the particular compressor you are buying. Are you confused yet? The compressor assemblies are called assemblies because they also have the dryer’s, valve bodies, switches, and control module all mounted on one large steel plate, Depending on how or who you buy the compressor from, it may have a control module or may not. Most do not and you will be hit with another $400 if you have to buy a control module.

3. You may also need the Air Spring Bags themselves, another $180-$200 each

4. Hopefully you have the parts you need to proceed and here comes the fun part. First of all, all the factory GM repair manuals for this repair are written for a professional technician that understands wiring schematics and proper repair procedures.

5. Many of the following procedures are really best done the way GM says they should be done, Altering or not using a scan tool to do these repairs can cause unknown and/or difficult to diagnose unintended  problems. If you read the instructions above on how to remove the compressor, then it is basically the same except when you put the new compressor into place and get it all connected, their are some procedures that really must be done with a scanner. These procedures are as follows:

a. Trim Height Calibration Procedure – With Scan tool in hand and connected, go to the air suspension section and under “Special Functions” you can find the calibration procedure, follow the instruction within the scan tool.

b. Air Pressure Pressurization Procedure – Located in the scan tool under “Special Functions”

c. Verify original trouble codes have bee repaired and cycle through the scan tool procedures to make sure all other components are working properly, During the initial diagnostic procedure, it is possible to not realize other failed components unless they set diagnostic trouble codes initially. If for instance your compressor failed, you go ahead and replace it and then you have a new trouble code for a level control sensor or worse a Suspension Control Module(suspension computer or brain). Most of the time a failed Suspension Control Module is found during the initial diagnosis, however if your compressor is failed, then you can not properly test the full functionality of the system  or control module until you put a compressor in it and try to restart the pressurization procedure. In other words, other problem parts are hidden and not able to be diagnosed from the beginning if you cannot get air into the system to check. The vehicle will go through its own process to set the proper ride height after a new compressor or air bags are installed. Hence this is when you discover another part needed that was not able to be identified during the initial diagnosis. This is the reason we say near the beginning of the article that the vehicle owner really needs to know all of the possible costs involved with the normal & continuous degradation of an air suspension system.

 

Taking a break, more to come soon…………………..

Joel

ASE Certified Auto Technician 16+ Years Of Auto Repair Experience

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33 Responses

  1. richie guadagno says:

    I HAVE A 2003 H2 I NEED NEW REAR COMPRESSER ,IS THERE ANY PLACE TO GET ONE CHEAPER

    • Joel says:

      Yeah their is really no cheap way out of it except converting it to a regular coil spring suspension. Look at the comment below and their is a link to the conversion kit. We sell the complete compressor and the airbags but the cheapest compressor is $1399.99 and the air bags are $185.00 each, You still have a computer, solenoids, & airlines that also may need replacing at some point.

  2. Tyler says:

    I have an 06 Hummer H2 I just purchased..only to find out days later that the compressor is completely gone ): ..and I now have to maunally fill air into the air bag lines nearly everyday to every other..Seems quite expen$ive to replace, any chance I can replace the airbags with coil springs like you have mentioned above? Anything that could be damaged or not correct by doing so? Please help..Thanks.

    • Joel says:

      Thanks Tyler, Here is a link to the coil spring conversion kit, At the time of typing this, the kit is $199.99 and free shipping in the continental US:
      http://www.apdty.com/searchitem.epc?lookfor=C2138

      Also we can get the compressors, although they are very expensive, around $1300-$1500, plus you usually need the airbags and possibly other parts so it gets even worse. Ill post a link to the compressor and air bags as soon as we load them into the website, Thanks

      • Tyler – you say you have to MANUALLY fill air into the air bag lines nearly every day – How are you doing this? My air suspension is not working at all and I can’t get it replaced until the 15th so I need to be able to drive it until then and i’m stuck!!!! Let me know if you can, thanks!!

  3. ramon says:

    i have a question i have a hummer 03 h2 and when i turn off the engine the rear shocks will stay up but sometimes go down . What should i do to fix that & how do you recommened i fix that ?

    • Joel says:

      You most likely have an air leak and have to find what is leaking. Most of the time a rear siick is leaking but you have to confirm that.myou can spray soapy water on each shock when they are full and watch closely for air bubbles. If a leak exists you may want to consider converting the vehicle to. On air ride as it can get very expensive to repair. Here is a link to the conversion kit Arnott C-2138 Coil Spring Conversion Kit\

  4. matt says:

    What if I want to leave the compressor attached so that I can still use it to fill bike tires, etc. for my kids. Is this possible? In other words, I already purchased the coils, but would like to still have use of the onboard compressor that is attached to the filling/hose assembly in the cargo area of my H2.

    Also, should I also replace the shocks in the rear at the same time? Will new shocks have any affect on the ride height after the coils are installed? In other words, will there be a visual difference in rear ride height if I install new shocks vs. just leaving the old ones on? Is the entire weight on the vehicle loaded on just the coils or is the weight shared by coils and shocks?

  5. Henry Morgan says:

    I have a 2006 Hummer H2 with about 600 miles on it it is a high security build truck with special equipment for vip backup security it came in with the rear suspension down.Here we have no Hummer dealer.do you have a wireing diagram for this truck .is there a suspension cut off switch like ford uses.I am an ASE certified Tech.and a former Ford sr master tech but no longer live in the us.Pease help if you can.

  6. Raymond says:

    Ok everything sounds cool, but my hummer H2 has a 6in suspension lift. Do you all my coils that would fit my hummer and would it be leveled?

  7. Harold says:

    You never finished the 2nd option in the post above regarding fixing the air suspension… look forward to reading it.

  8. Mark says:

    Hi I have just fitted coil springs to a H2 but now have a message on the dash says suspension failure does this need to be reset by dealer

    • Karen Parker says:

      According to the instructions above, the compressor module being disabled / removed should deactivate the error msg. However, I cannot confirm this bc I, too, had my 2004 H2 converted but the compressor, etc was not removed & is still in tact. It seemed to be disabled for over a yr until my alternator had to be replaced & is now “active” again. All the while, the error msg on my dash in reference to the suspension needing repair has NEVER gone away. The mechanic said he didn’t know how to get rid of it. Could you take a peak & see if your compressor, etc is still there although you had the conversion done? I’m wondering if yours has been left in tact as mine was or if it was removed, I would know not to get my hopes up that it will go away once I disconnect the module. If it is still there, maybe disconnecting the module will work for us both as indicated above! Thanks so much!

  9. Karen Parker says:

    About a year & a half ago, I had a fellow come out & replace my air springs w/ the coil springs on my 2004 H2. No problems or issues at all – til now. Recently, my alternator had to be replaced. Once that was done, I started getting the constant clicking of the air ride compressor every time I got out of the vehicle. So now, my H2 clicks constantly. Obviously, the fellow that converted my springs for me did not remove the compressor. I eventually will just do that myself but w/ a lack of time, what can I do to disable it? I can’t see all the parts of the compressor w/out the rear wheels being removed, etc so where should I be feeling to find the module to disconnect it, which I’m assuming is what needs to be done. There are 2 “plugs” mounted on the outside of the “carriage” for the compressor. Could one of them be what I need to unplug & if so, which one?? There’s a smaller & a larger one. Thanks for any help!

  10. Karen Parker says:

    I’m guessing no one maintains this page any longer. Bummer!!

  11. Joel says:

    Hi Karen, 9 times out of 10, you can disable the light by unplugging the compressor and both plugs should be unplugged. The entire compressor assembly is good to remove as it is fairly heavy and leaving it in place just eats gas mileage. It is very rare but if the light stays on, then it is possible their is a bad ground somewhere and this would have to be figured out by a professional technician that can trace that down. We have sold hundreds of the conversion kits and most all of them had the light go out by removing the compressor assembly. Thanks

  12. Joel says:

    This post is to answer several of the above questions.
    1. You can remove or unplug the suspension compressor to get rid f the light
    2. If you still want to use the air compressor to fill anything needing compressed air, then you can leave the system completely intact or convert it, if you convert it, you would most likely need to replug in the compressor every time you want to use it. That may not be the greatest thing to do as the system will try and go through some system checks and it will turn the light on each time it is plugged in. The best thing if you convert it is probably a cheap little plug in compressor.
    3.if you have a lift on the vehicle, the first question is what type of lift and depending on the kit you get you will probably get rear springs. The conversion kit that we sell will work on any standard non modified truck and will probably fit most lift kits but you would need to ask the lift kit manufacturer as they make several different types.
    4. Shocks – The shocks really do nothing for the ride height, the coil springs or airbags set then ride height and the shocks are only for support and to dampen the jounce of the coil springs. Replacing shocks when new coil springs are installed is always a good idea, otherwise a common rule of thumb is around 50k miles to replace them. Also an alignment should be performed when replacing coil springs, you do not née dot do an alignment if you only replace shocks as again they do not affect the ride height.

  13. don says:

    Hello, I have a 03 h2 and I have code co631 right side sensor, what I need to know is if I replace this will I have to have the hole system calibrated again or will it just reset and work fine again,, also is there a jumper you can use in the wire harness to manualy let the air out or do you have to remove the carrier and take a line off to drop it from full lift.. thanks

  14. Justin says:

    I have a 2005 H2 with the airbags. I raised the front and wanted to raise the rear 1.25 inches. Is it possible to just put a spacer under the rear air bags to raise it? Or is there a better way?

  15. Gonzalo says:

    Hello Everybody,

    I have a question I just purchased a 2003 hummer h2 4×4 I have noticed that when I park it and leave it over night the rear end lowers all the way down but when I turn it on it goes back to its normal possession is that normal or can I fix that using the height control or would it be a suspension problem?

  16. Stephen Dennison says:

    Joel / Gents

    My 2003 Hummer has an intermittent sagging … sometimes it stays up for days and days … sometimes it goes down overnight … the compressor always brings it up to snuff when you start it up. I suspect a problem with the Air Compressor Control Module or the positions sensors … can you suggest a course of action … it’s my wife’s hummer and she’s driving me nuts … the dealer is suggesting a 100% replacement at something close to the Gross National Product of Malaysia and she keeps wanting to do that which, as you suggest, is insane … thanks in advance

  17. Henry Cruz says:

    The back of my 2004 H2 goes down when parked overnight and goes back up as soon as I start and drive it. Sometimes you can hear a clicking noise in the back after driving. Could there be a leak somewhere and can I do it myself?

  18. Freddy says:

    Hey i got a question I have my car n it says service air suspension n it won’t go up I has someone check it they said it was the pressure sensor I went to the dealer n they discontinue tha piece is a lil silver piece next to the compressor n it says sensor how can I get it anyone can help me

  19. Rademakers says:

    Hi,my 2003 also had air ride problems.
    Not anymore: we removed the system,disconnected the airlines and joint them back together with a airline to the inflation point(in the rear side interior)
    Although I must admit I have a auxiliary compressor in the car( carry on,cheap), I only have to inflate every other 2 months.
    Regards

  20. Marisa Dugas says:

    My husband was in a accident with our 2014 H2 SUT the car was almost totaled. It was in the shop for over to months and still things are not right. Most importantly none of the airbags deployed and my husband still hasn’t recoved from is injures. Any advise from someone would greatly be appreciated

  21. Marisa Dugas says:

    2008 H2 SUT not 2014

  22. ocimar says:

    i have a question i have a hummer 03 h2 and when i turn off the engine the rear shocks will stay up but sometimes go down . What should i do to fix that & how do you recommened i fix that ? –

  23. Dan says:

    Hi,
    So are all compressor/ dryer/module platform from 2005 and up interchangeable?

  24. Tom says:

    I have a 2005 hummer h2 with air suspension I have a fab tech 6 inch lift I heard a big pop come from the rear and now my rear end is low riding can i put in that conversion kit so it’s not air suspension anymore? please let me know thanks.

  25. Ziad says:

    h2 2003
    I’ve replaced the rear air suspension bags with springs ,but a problem occurred
    it always says on the dashboard ” check rear suspension” that is because the air lines are free
    do you recommend to block the lines with screws or any other thing or just take the electrucal fuse out and where that might be ?!
    Thanks ppl
    Ziad
    ziadalasmar69@gmail.com

  26. Craig says:

    Hi guys. Just got a 04 Hummer H2. The truck has been converted to coil springs in the back. Ive been browsing though this and other web sites trying to find a solution to the “service air ride” message on the cluster. Arnott does not make a “bypass module” for this truck. How do I eliminate this message or is it just always going to be there? I called a GM dealer I know to see if they could disable it via the GM computer and he did not seem to think they could. Any suggestions or solutions appreciated. Thanks.

  27. Ms says:

    Hummer H2 2008-2009 Air Ride Suspension Compressor With Dryer I want so please send price ,photos delivery time to Malaysia tq

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