BENDIX AD-IS AIR DRYER

Questions and Answers

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Kenneth LewisAug 16, 2025
How to troubleshoot a BENDIX AD-IS AIR DRYER if it cannot build system air pressure?
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  William FergusonAug 16, 2025
  If the BENDIX Dehumidifier cannot build system air pressure: * Check for a kinked or blocked (plugged) discharge line to determine if air passes through it. Look for kinks, bends, excessive carbon deposits, or ice blockage. * Ensure the discharge line has as few bends as possible and constantly slopes from the compressor to the air dryer, as excessive bends can collect water and freeze. * If the pressure protection valve(s) in the air dryer will not open, replace the air dryer (pressure protection valves are not serviceable). * Refer to Symptom 4, Remedy A. * Refer to Symptom 7, Remedies A and B.
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Dennis JohnsonAug 28, 2025
Why is the safety valve on my BENDIX AD-IS AIR DRYER popping off or exhausting air?
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  darren49Aug 28, 2025
  The safety valve on the BENDIX Dehumidifier might be popping off or exhausting air due to: * A defective AD-IS® air dryer and reservoir system delivery check valve. Test to determine if air is passing through check valve. Repair or replace. Refer to Symptom 1, Remedy B. * The safety valve setting being too low (less than 150 p.s.i.). Replace the safety valve. * The system pressure being too high (greater than 135 p.s.i.). Test with an accurate gauge and replace the governor if necessary. * Excessive pressure pulsations from the compressor, especially in single-cylinder types. Increase the volume in the discharge line by adding a 90 cubic inch (or larger) reservoir between the compressor and the AD-IS® air dryer and reservoir system.
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David SmithAug 31, 2025
Why is desiccant material being expelled from the BENDIX Dehumidifier purge valve exhaust?
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  lisahowardSep 1, 2025
  Desiccant material might be expelled from the BENDIX Dehumidifier purge valve exhaust due to: * A faulty dryer cartridge. Replace the AD-IS® air dryer cartridge and/or AD-IS® air dryer. * Excessive dryer vibration. Check the AD-IS® air dryer mounting for looseness or damage. Repair the mounting and replace the cartridge.
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michaelmcguireSep 4, 2025
What to do if the BENDIX AD-IS AIR DRYER does not purge or exhaust air?
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  Sherry MorenoSep 4, 2025
  If the BENDIX Dehumidifier does not purge or exhaust air: * The air dryer purge valve may be faulty. After determining air reaches purge valve control port by installing a T-fitting with a pressure gauge into the governor unloader port, repair purge valve if necessary. * Refer to Symptom 4, Remedies B, E, and F. Also refer to Symptom 1, Remedy B.
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Susan BradleySep 8, 2025
What causes unsatisfactory desiccant life in BENDIX AD-IS AIR DRYER?
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  gary95Sep 8, 2025
  Unsatisfactory desiccant life in the BENDIX Dehumidifier can be attributed to: * Excessive system leakage. Refer to Symptom 1, Remedy A. * Using the wrong vehicle application for the AD-IS® air dryer. Refer to Symptom 2, Remedy C. * The compressor passing excessive oil. Check for proper compressor installation; if symptoms persist, replace the compressor. Refer to Bendix Advanced Troubleshooting Guide for Air Brake Compressor (BW1971).
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Nathan LopezNov 11, 2025
What to do if there is constant exhaust of air at the BENDIX Dehumidifier purge valve or the system pressure won't build?
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  Jasmine RobersonNov 12, 2025
  If there's constant air exhaust at the air dryer purge valve or the system pressure won't build on your BENDIX Dehumidifier, consider the following: * The air dryer purge valve may be leaking excessively. With the compressor loaded, apply soap solution on the purge valve exhaust to test for excessive leakage. Repair or replace the purge valve as necessary. Refer to Technical Bulletin TCH-008-040. * The purge valve might be frozen open due to a faulty heater and thermostat, wiring issues, or a blown fuse. Refer to paragraph 5 of Operation and Leakage Tests for heater and thermostat test. * A defective AD-IS® air dryer delivery check valve could be the cause. Refer to Symptom 1, Remedy B. * A leaking Turbo Cut-Off valve may be the issue. Repair or replace the purge valve assembly. *...
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Nicholas RodriguezNov 19, 2025
Why is there water in the BENDIX AD-IS AIR DRYER vehicle reservoirs?
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  Jessica MasonNov 19, 2025
  Water in the vehicle reservoirs of the BENDIX Dehumidifier can occur due to several reasons: * The maximum air dryer inlet temperature is exceeded because of an improper discharge line length. In this case, check for excessive carbon build-up in the compressor discharge line and replace it if needed. Ensure the discharge line is at least 6 ft long. Increase the discharge line length and/or diameter to reduce the air dryer inlet temperature. * The air system is charged from an outside air source that doesn't pass through the air dryer; if using an outside air fill, ensure it passes through the air dryer. * There is excessive air usage, making the air dryer incompatible with the vehicle air system requirements. Refer to the Bendix Advanced Troubleshooting Guide for Air Brake Compresso...
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jwheelerNov 23, 2025
Why is my BENDIX AD-IS AIR DRYER constantly cycling or purging?
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  Rachel WrightNov 23, 2025
  The BENDIX Dehumidifier might be constantly cycling or purging due to: * Excessive system leakage. Test for excessive system leakage. Allowable leakage observed at dash gauge: Single vehicle - 1 psi/minute. Tractor trailer - 3 psi/minute. Using soap solution, test vehicle for leakage at fittings, drain valves and system valves. Repair or replace as necessary. * A defective delivery check valve. Build system pressure to governor cut-out. Wait 1 minute for completion of purge cycle. Using soap solution at exhaust of purge valve, leakage should not exceed a 1" bubble in less than 5 seconds. If a rapid loss of pressure is found, the following procedure will determine if the delivery check valve is malfunctioning: Build system pressure to governor cut-out and allow a full minute for the no...