RV Air Suspension Issues Explained(+Topmost Common Problems)

In this brief article we are going to discuss the different RV Air Suspension problems, what the causes are, and Troubleshooting Tips.

What are the most common RV Air suspension issues? 

The most common  RV Air suspension issues are:

  • Corner suspension sag
  • Suspension Leaning to one side
  • Suspension dropping during overnight parking
  • Air suspneinos warning light

RV Air Suspension Set-up

The  RV Air Suspension is a load sharing independent suspension used in Leading Trailer Manufacturers, and Transportation Companies.

The Tandem axle arrangement is meant to perfectly balance the 2 axles in terms of load bearing. The design is in such a way as to maintain equal distribution of weight across the 2 axles in any given road condition.

Different Types of  RV Air Suspension Products

THe 2 main types of air suspension for RV’s are 

  • Full Air suspension
  • Semi Air suspension

Full Air Suspension

  • Full air suspension means that the only springs in the suspension are the Air Springs or Air Bags. 
  • There will be no leaf springs or coil springs.
  • The advantage of this type of suspension is that you can have a softer ride quality, as compared to the Semi Air Suspension

Semi Air suspension

  • Semi Air Suspension means that the Air suspension is only a helper to the conventional leaf spring or coil spring suspension
  • The Air Springs or Air Bags will be connected to the chassis in parallel to the conventional steel springs
  • The Disadvantage of the Semi type is that the ride quality would be stiffer, because springs fitted in parallel always add up in stiffness

In both of the above cases, the vehicle will have the capability of adjusting its ride height and also self-levelling to maintain a certain predetermined ride height setting when there is a change in the load of the vehicle.

Corner Suspension Sag or Front/Rear Sag

  • The Corner Sagging problem is the most common to all RV Air suspension systems
  • The Symptom is that one of the Corner suspensions loses ride height after being parked overnight
  • In some cases, both sides (left and right) have lost height on either the front or the rear suspension

Root Cause:

  • There are 3 potential reasons for ride height loss on parking:
    • Faulty Ride height sensor
    • Air Spring Leakages
    • Valve-Block Defect
    • Faulty Air Compressor
    • Shock Absorber Leakage
  • Air leakage related suspension sagging generally is seen when the RV is parked overnight and sometimes even over a period of days.
  • This fault can be confirmed using the manufacturer’s recommended Scanning/Diagnosis tool.
  • Before starting the diagnostic scan, make sure to clear all Fault codes that have already been stored
  • Start the vehicle and try to lift the vehicle by selecting “Lift” option
  • However, if diagnostics is not available on your RV, then you can simply follow the sequence to troubleshoot would involve looking at each of the suspension elements in the following order

Troubleshooting Corner Sagging: Compressor Failure

  • If the compressor ‘humming’ sound can be heard, and the suspension is not able to lift, it could be a case of a failed compressor
  • The Air Compressor tends to corrode over long-term use and internally wears out. Even if the compressor runs, it fails to develop the required pressure.
  • Although it would be best to replace the compressor, there are good chances that you could purchase a compressor ‘Rebuild Kit’ and attempt to Rebuild the compressor for your RV.

Troubleshooting Corner Sagging: Ride Height Sensor Linkage

  • You need to Scan the Fault codes with the Ignition ON
  • Error codes that point to “Level Control system sensor” indicate that the ride height sensor linkage is a probable issue.
  • The faulty linkages need to be corrected or replaced.
  • After making the rectification, if there is a difference in height between the left and right side in the front and the back, it can be corrected by doing a height calibration. 
  • The steps to do a height calibration would be different for different RVs. While some OEM’s have a mechanical lever adjustment, others come with an automatic computer-controlled calibration that can be done through the OEM Diagnostic Tool

Troubleshooting Corner Sagging: Air Spring Leakage

  • If the Ride height sensor linkages were not the issue, the next most probable cause would be an air leakage somewhere in the air suspension air circuit.
  • In the case of air leakages, the system does often detect and display the error code.
  • But, however, there have been many cases where confirmed leakages were not detected by Diagnostics. Whether diagnostics is available on your RV or not,you invariably need to manually inspect leakages and identify the points of leakage
  • Air springs are known to wear out and crack at the rubber bellow surface gradually after accumulating mileage. They generally would last 70K to 80K miles depending on usage.
  • In a high mileage vehicle, the air springs would be the first place to check for leakages.
  • Fill the Air springs by either 
    • Turning ON the ignition, or
    • In the Diagnostic tool, use the “Air Filling/Venting Set-up” Inspection/Test to fill air into the system, OR 
    • If the diagnostic method is not possible, then you can pressurize the air spring through the inlet using an external air compressor
  • Once the air springs are inflated, you need to spray springs with soap solution to check for leaking.
  • After spraying the soapy water solution, wait to see if there are white foam bubbles that stay at one spot even after wiping it with a finger.
  • In cases where the leak is major, you even hear a hissing noise coming from the leakage point and be able to locate it by ear.
  • Once you have confirmed that there indeed is a leak, the air spring has to be replaced. 

Troubleshooting Corner Sagging: Valve-Block Leakage or Defect

  • The valve block opens and closes valves to the individual air springs when it gets a signal from the air suspension ECU
  • When the valve block fails to appropriately open the valves to the air springs and supply air, the vehicle suspension sags
  • The DTC (Diagnostic Trouble Code) will mostly show up as a general fault in the air suspension. In some vehicles, the code is more specific and the DTC points to the valve block as the source of the fault
  • Locate the Valve block in the underbody of the vehicle
  • Use a soapy water spray to detect bubbles at the valve block air connector fittings
  • If there is a crack or damage at the valve block body, then it will need to be replaced.
  • Suppose there were no cracks/damages or leakages, then you need to check whether the valve is properly sending air to the individual air struts. This can be done using the diagnostic tool. OR, you can remove the valve and test it manually, checking for pressure at each solenoid valve.

Suspension Leaning to one side

  • The Air Suspension, sometimes, makes the RV lean to one side due to daily use and wear in the suspension. But at the same time the suspension is not fully sagging.
  • The Self-adjust mechanism of the suspension does not Level the RV Flat, or in other words, one side (either left or right) 
  • Ride height is self-adjusted by the Suspension System at a different ride height at one corner, compared to the opposite side.
  • In most RVs, this sort of difference in ride height can be corrected by doing a height calibration. Depending on the vehicle, the calibration is done either manually by adjusting the ride height sensor levers or electronically, through the air suspension ECU using a diagnostic tool procedure.

Calibrating the Adaptive Air Suspension

  • You need to refer to the instructions issued by your RV OE Air suspension supplier for ride height calibration
  • What happens often is that a sudden impact to the tires from the road would have knocked off the sensor calibration out of position from the initial calibration that was done by the OEM
  • The lever mechanism of the Ride height sensor will always contain a slotted adjustment to raise or lower the reference at any of the corners.
  • Locate this and adjust according to the OE instructions

Suspension Dropping during overnight parking

  • Loss of ride height after long hours of parking is also a highly common symptom of suspension malfunction in most RVs
  • Most of the RVs’ Air suspension ECU would throw a warning indication on the dash continuously until the fault is rectified
  • When the suspension drops and is unable to raise itself, in many cases, the Air compressor would not be functioning

Troubleshooting Suspension Dropping: Electrical Fault

  • It would be best to Diagnose a suspension warning indication using a Scanner diagnostic Tool
  • If the Fault Code shows an electrical connector fault then first examine the Valve block connections
  • Remove and Check the Valve Block connector terminals for corrosion and clean if necessary
  • If the Fault Code points to the vehicle leveling front sensor, it mostly also shows which of the sensors is at fault
  • Start by first checking for voltage reading at the faulty sensor through the diagnostic tool, and then checking the electrical continuity at the faulty height sensor connector
  • If needed, replace the particular faulty corner height sensor
  • However, if diagnostics is not available on your RV, then you can simply follow the sequence to troubleshoot would involve the traditional way of referring to the circuit diagram and checking for electrical continuity in each of the circuits.

Air Suspension warning light

  • Most RVs flash a yellow suspension warning light to show a fault in the ride height adjustment
  • In many cases, when pressing the ride height adjust button, the height does not change
  • In many other cases, one or more of the Corner suspensions loses ride height after parking

Root Cause:

  • The loss of suspension height, could be due to multiple reasons, the two main ones being:
  • Air leakages somewhere in the system
  • Valve Blockages
  • A slow air leakage causes sagging generally when the RV is parked overnight and sometimes even over a period of days.
  • This fault can be confirmed using the OE Scanning/Diagnosis tool
  • Before starting the scan clear all Fault codes that have already been stored
  • Start the vehicle and change suspension height to lift the vehicle by selecting “Lift” option

Troubleshooting Suspension Warning Light: Leakage

  • You need to Scan the Fault codes while the vehicle suspension is trying to lift itself. This can be started by setting the suspension to ‘Lift’ mode.
  • In the case of leakages, the system does detect and display the concerned error code
  • Air springs are known to wear out and crack at the rubber bellow surface gradually after accumulating mileage. They generally would last 70K to 80K miles depending on usage.
  • In a high mileage vehicle, the air springs would be the first place to check for leakages.
  • Fill the Air springs by either 
    • Turning ON the ignition, or
    • In the Diagnostic tool, use the “Air Filling/Venting Set-up” Inspection/Test to fill air into the system, OR 
    • If the diagnostic method is not possible, then you can pressurize the air spring through the inlet using an external air compressor
  • After spraying the soapy water solution, wait to see if there are white foam bubbles that stay at one spot even after wiping it with a finger.
  • In cases where the leak is major, you even hear a hissing noise coming from the leakage point and be able to locate it by ear.
  • Once you have confirmed that there indeed is a leak, the air spring has to be replaced.

Troubleshooting Suspension Warning Light: Valve-Block Leakage

  • The DTC (Diagnostic Trouble Code) will mostly show up pointing to a malfunction in the Valve Block
  • Use a soapy water spray to detect bubbles at the valve block air connector fittings
  • If there is a crack or damage at the valve block body, then it will need to be replaced.

Tips on Replacing the Air Springs

  • Before removing the air spring for replacement, be sure to relieve the air pressure from it at the valve block, which is located in the underbody near the rear bumper.
  • Relieve the left or right air spring valve by loosening the connector gradually. If this is done suddenly, then you could risk damaging the O-rings within the air connector fitting.
  • While replacing the Air Spring, be sure to cut off the portion of the line that was squeezed or stretched in the old fitting after disconnecting. The reason being that the old used portion  of the air line could crack and cause a potential leak.

Pro-Tip:

  • ?In most RVs, aftermarket brand replacement bellows tend to give a higher service life as compare to the original OE spare part
  • Moreover, some aftermarket replacement parts also come with a lifetime warranty instead of a limited warranty offered by manufacturer

Tips on Rebuilding the Air Suspension Compressor

  • An air compressor is expensive to replace new, and in many cases almost close to the resale value of the RV
  • Many owners try to DIY the compressor with repair kits available from small companies
  • To check for compressor issues, you need to dismantle it and examine the Piston, Cylinder and Piston ring condition.
  • The compressor seizes mostly due to overheating. The parts that get damaged first are the Piston Ring and the O-seals that make the compressor air-tight. A repair kit would mostly consist of a set of Piston rings and a set of o-rings that suit the particular OE compressor unit.

The rebuild option does come with risks as there could be issues in the compressor other than just the piston and rings.

Conclusion

In this brief article we have discussed the different RV Air Suspension problems, what the causes are, and Troubleshooting Tips.

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