Meritor Wabco System Saver Series

Questions and Answers

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Louis PaceAug 22, 2025
Why does Meritor Wabco System Saver purge too often?
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  Mary RitterAug 22, 2025
  Your Meritor Wabco Dehumidifier might be purging too often due to several reasons. There could be a leak in the line between the governor and dryer port 4, or in the line between the supply tank and the governor. Excessive air system leaks or demands can also cause this issue. Inspect and replace the outlet check valve or regeneration valve as needed. The air governor might have less than a 16 psi range, or there could be leaking air compressor unloaders. Repair any air lines or system leaks. If air system demands are too high, increase the air system capacity or reduce the air demand. Replace the air governor, and inspect the compressor, repairing or replacing it as needed.
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Robert HerreraAug 25, 2025
What to do if Meritor Wabco System Saver Dehumidifier does not purge when compressor unloads?
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  Samantha WongAug 25, 2025
  If your Meritor Wabco Dehumidifier isn't purging when the compressor unloads, start by checking the air line between the governor and air dryer port 4 for kinks or plugs; repair the air line if necessary. The purge valve might be stuck closed, in which case you should replace it. Inspect the air governor and repair or replace it according to the manufacturer’s instructions. Also, verify that the air compressor is achieving the cut-out pressure. Check for air leaks in the system and repair them as needed. If there are no leaks, check the compressor output and repair or replace it per the manufacturer’s instructions.
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Patrick PatrickAug 26, 2025
How to troubleshoot no air pressure build-up in Meritor Wabco System Saver system?
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  Candice MontoyaAug 26, 2025
  If there's no air pressure build-up in your Meritor Wabco Dehumidifier system, first ensure the air dryer is plumbed correctly: the compressor discharge line should connect to air dryer port 1, and air dryer port 21 should connect to the vehicle’s supply tank. Also, verify that the dryer port 4 line connects to the “UNL” port of the air governor. Inspect the governor per the manufacturer’s instructions, repairing or replacing it as needed. Locate and repair any air system leaks, such as those in the compressor discharge line, air dryer, reservoirs, or brake and suspension valves. Check for air dryer leaks from the purge valve.
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patrick80Aug 27, 2025
What causes water in tanks after installing Meritor Wabco System Saver?
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  patricia96Aug 27, 2025
  If you find water in the tanks after installing a Meritor Wabco Dehumidifier, especially as an aftermarket installation or replacement, it may be due to the pressure-controlled check valve not being installed in the correct tank or not installed at all. Install the pressure-controlled check valve in the secondary tank. Another cause could be that a one-way check valve was not removed when the pressure-controlled check valve was properly installed. Remove the one-way check valve so that only the pressure-controlled check valve is installed between the secondary tank and supply tank.
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flemingsamanthaAug 29, 2025
Why is Meritor Wabco System Saver Dehumidifier regeneration cycle too long?
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  Joseph WongAug 29, 2025
  If the regeneration cycle of your Meritor Wabco Dehumidifier is too long (more than 30 seconds), accompanied by a loss of pressure in the supply tank, it could be due to the outlet check valve not seating properly or the regeneration valve not shutting off regeneration airflow. Inspect and replace the outlet check valve as needed. Replace the regeneration valve.
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Joel LeonardAug 31, 2025
What causes Meritor Wabco Dehumidifier to be frozen?
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  Amanda UnderwoodAug 31, 2025
  If your Meritor Wabco Dehumidifier is frozen, with water collecting in the base and freezing, it could be due to several reasons. Check for a blown fuse in the heater circuit and repair it. Ensure there is electrical power to the heater connector whenever the vehicle’s ignition is ON. Low voltage to the heater connector can also cause freezing; repair any causes of low voltage, such as poor electrical grounds, bad connections, or corroded wire splices. The heater assembly itself might not be working, so replace it if necessary. Finally, ensure you are using the correct voltage air dryer; for example, do not use a 12-volt air dryer in a 24-volt system, replace with correct voltage air dryer.
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Julie RoachSep 2, 2025
What to do if there is water in Meritor Wabco System Saver purge tank?
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  ebrownSep 2, 2025
  If you find water in the purge tank of your Meritor Wabco Dehumidifier, there may be a block in the purge tank line. Clear the blockage and replace the desiccant cartridge.
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Stanley GallagherSep 4, 2025
What causes slight leak from Meritor Wabco System Saver Dehumidifier purge valve?
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  Rachel SalasSep 4, 2025
  A slight leak from the purge valve of your Meritor Wabco Dehumidifier, which may empty the supply tank after several hours, is often caused by the outlet check valve not seating properly or the regeneration valve not shutting off regeneration airflow. Remove, inspect, and clean the outlet check valve and regeneration valve diaphragm. Replace if worn or damaged.
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Stacy DiazSep 6, 2025
Why is there no airflow from Meritor Wabco System Saver purge valve after initial purge blast?
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  Maria RileySep 6, 2025
  If there is no airflow from the purge valve after the initial purge blast on your Meritor Wabco Dehumidifier, it could be due to several reasons. The air dryer might not be connected to the supply tank, or the connections might be reversed at the dryer. Verify proper dryer installation per the system diagram. The regeneration valve might not be working, so replace it. A one-way check valve might be installed in the supply tank; remove it. If an alcohol evaporator is installed between the dryer and supply tank, install a bypass line around the evaporator or remove the evaporator from the system. Also, check for a blocked or pinched line from the purge tank and clear or repair the line.
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matthew52Sep 8, 2025
What does it mean when air flows out of Meritor Wabco System Saver purge valve the entire time compressor is unloaded?
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  Katie PatrickSep 8, 2025
  If air flows out of the purge valve the entire time the compressor is unloaded on your Meritor Wabco Dehumidifier, the turbo cut-off valve may not be sealing properly. Replace the turbo cut-off valve. Note that with U Series air dryers, a steady flow of air is normal as the compressor unloads through the dryer.

Summary

Service Notes

Before You Begin

Instructions to follow before starting service procedures.

Access Product and Service Information on our Web Site

Information on accessing product and service data online.

To Order Information by Phone

Contact details for ordering technical information.

Safety Alerts, Torque Symbol and Notes

Explains warning, caution, note symbols and torque symbol meanings.

Section 1: Introduction

System Overview

Overview of the manual and air dryer series.

Air Dryer Documentation

Lists available documentation for air dryers.

Air Dryer Identification

Explains how to identify different air dryer models.

How the Air Dryer Works

Explains the functional principle of the air dryer system.

Air Dryer Cycle

Details the operational sequence of a single cartridge air dryer.

Air Dryer Components

Identifies and illustrates replaceable parts of the air dryer.

Dryer Identification

Details about the identification tag on the air dryer.

Description of Components

Describes individual replacement components for single canister air dryers.

Heater

Describes the air dryer heater, its function, and availability.

Bypass Valve

Explains the bypass valve, its function, and usage by date code.

Outlet Check Valve

Describes the outlet check valve and its function.

Pressure-Controlled Check Valve (PCCV)

Explains the PCCV, its use with regeneration style dryers, and mounting.

Pressure Relief Valve

Describes the pressure relief valve and its installation.

Purge Valve

Explains the purge valve, its location, and function.

Regeneration Valve

Describes the regeneration valve and its operation.

ECON Valve Replacement Part

Details the ECON valve part for specific dryer models and compressor types.

ECON Valve

Explains the ECON valve's installation requirements for specific compressor types.

Turbo Cut-off Valve

Describes the turbo cut-off valve, its function, and specific models.

Heater Power Harness

Describes the heater power harness and its connection.

Purge Silencer

Describes the optional purge silencer for noise reduction.

Section 2: Troubleshooting & Testing

Routine Maintenance

Recommended routine maintenance tasks for the air dryer.

Maintenance Tips

Helpful tips for ensuring reliable service and protection.

Troubleshooting

Table of common conditions, possible causes, and solutions.

System Tests

Heater Resistance

Procedure to check the resistance of the heater element.

Leak Test

Procedure to test air system connections for leaks using soap solution.

Air Pressure Checks

Guidelines for accurate air pressure readings using calibrated gauges.

Operational Test for System Saver Series Air Dryers - Regeneration and Purge Style

Test to verify the air dryer's regeneration and purge cycle operation.

Pressure-Controlled Check Valve Test - Regeneration Style Only

Test procedure for the pressure-controlled check valve on regeneration style dryers.

Section 3: Installing Replacement Parts

Replacement Requirements

General requirements and reasons for replacing air dryer components.

Component Replacement

General steps for component replacement, including safety precautions.

Desiccant Cartridge

Step-by-step guide for replacing the desiccant cartridge.

Outlet Check Valve Assembly

Instructions for replacing the outlet check valve assembly.

Heater Assembly

Step-by-step instructions for replacing the heater assembly.

Turbo Cut-Off Valve Assembly

Instructions for replacing the turbo cut-off valve assembly.

Regeneration Valve Assembly

Instructions for replacing the regeneration valve assembly, including diaphragm types.

Purge Valve Assembly

Step-by-step instructions for replacing the purge valve assembly.

Pressure-Controlled Check Valve (PCCV)

Instructions for replacing the pressure-controlled check valve.

Bypass Valve

Instructions for replacing the bypass valve, applicable to older models.

Pressure Relief Valve

Instructions for replacing the pressure relief valve.

Purge Silencer (Muffler)

Instructions for installing the optional purge silencer.

Air Dryer Assembly

Procedure for removing and replacing the entire air dryer unit.

Testing the Meritor WABCO System Saver Series Air Dryer

Procedure to test the installed Meritor WABCO System Saver Series Air Dryer.

Appendix I: Glossary

Basic Air System;Air Dryer Terms

Definitions of common terms related to air systems and dryers.

Appendix II: Application Information

General Requirements

General installation and operating requirements for air dryers.

Operating Environment Requirements

Specifies operating parameters like temperature and voltage.

System Saver Series Installation Criteria

Installation criteria and specifications for System Saver Series air dryers.

Appendix III: Special Applications

Holset E-Type Compressor Systems

Information on using air dryers with Holset E-type compressors and the ECON valve.

ECON Valve

Details on the ECON valve, its function, and installation for specific dryer models.

Alcohol Evaporator

Information on checking for and managing alcohol evaporators in the air system.

Combo Tank Installation for Regeneration-Style Air Dryers

Diagram illustrating combo tank installation for regeneration-style air dryers.

Component Replacement Guide

Visual guide for replacing major components of the air dryer.