800765BXW | Genuine Bendix® AD-T Trailer System Guard Air Dryer

1. Removes Moisture From Compressed Air

Prevents water from entering the air brake system, which could freeze, corrode components, or cause brake failure.

2. Filters Out Oil and Contaminants

Protects valves, chambers, and lines from debris that can cause sticking or malfunction.

3. Regulates and Maintains Clean Air for Trailer Brakes

Ensures that the trailer receives clean, dry, safe air for reliable braking performance.

4. Protects the Entire Trailer Brake System

Works as a “system guard” to maximize the service life of:

• Relay valves

• ABS valves

• Brake chambers

• Control circuits

5. Improves Safety and Reliability

Clean, dry air reduces the risk of brake fade, sticking valves, and unpredictable trailer braking behavior.

• Water drains from the trailer air tanks when you open the drain valves.

• Excess moisture is the #1 indicator of a failing air dryer.

2. Frozen Brakes in Cold Weather

• Moisture entering the air system freezes in lines or valves.

• Trailer brakes stick, lock up, or fail to release.

3. Contaminated or Oily Air Lines

• Oil or sludge seen in valves, chambers, or air lines indicates the dryer is not filtering oil properly.

4. Frequent Purging or No Purging

• Rapid purging from the dryer means internal valves may be stuck.

• No purging during compressor cycles means the purge valve may have failed.

5. Air System Slow to Build Pressure

• Trailer takes longer to reach proper brake pressure.

• Indicates air leaks, stuck check valves, or moisture blockage caused by a bad dryer.

6. Trailer Brake Valves Sticking or Malfunctioning

• Relay valves or ABS valves respond slowly or inconsistently due to contaminated air.

7. Corrosion in the Air Brake System

• Rust inside tanks, valves, or fittings means water is getting past the dryer.

8. Excessive Desiccant Dust

• White or yellowish powder in air lines or valves shows the desiccant cartridge is breaking down.

9. Air Leaks at the Dryer

• Hissing sound or visible air leak around:

  • Purge valve

  • Fittings

  • Check valves

10. Brake Performance Issues

• Trailer brakes may:

  • Apply unevenly

  • Release slowly

  • Lock unexpectedly