6 Ways to Troubleshoot Your Haldex PURest Air Dryer

Why You Need to Pay Attention to Your Air Dryer

If you've been part of the trucking industry for a while, then you know about the increasing importance of your vehicle's air system. As vehicles work to optimize uptime and become more fuel-efficient, more and more air-braked vehicles depend on clean, quality air from their air dyers to keep solid, liquid, and aerosol contaminants – like water and oil – out of the air brake system.

Located between the compressor and the reservoirs, air dryers are responsible for removing these contaminants before they affect the air system and potentially jeopardize the vehicle's efficiency. ABS components, push-pull dash valves, spring brake modulating valves, seals, and other components in your air brake, engine, and drivetrain systems can all experience premature failure due to oil contamination if your air dryer isn't working at full capacity.

The PURest air dryer from Haldex, featuring a multi-treatment cartridge that employs five stages of cleaning to produce clean, dry system air, is one of the most popular models in use today. Here are six common ways to troubleshoot your PURest air dryer and what repairs may be necessary to keep your air system at peak performance.

1. Water in the Air System

Causes: If there's water in your air system, this could potentially be attributed to contaminants in the desiccant or leaks in the air system.

How to fix it: Desiccant contaminants can be addressed by changing the desiccant cartridge and checking the compressor for excessive oil passage. To check for air system leaks, tighten the air connection, soap the connection, and recheck for leaks per Haldex's manufacturer instructions.

2. Constant Exhaust of Air at Air Dryer

Causes: This could be due to a defective dryer outlet check valve.

How to fix it: Clean the valve seat, replace it, and check the valve again.

3. Excessive Compressor Cycling

Causes: There are three different reasons you may be experiencing excessive compressor cycling. You may have excessive leakage in the air system, a defective dryer outlet check valve, or you may also have a compressor that's undersize. The duty cycle of the compressor should not exceed 25 percent.

How to fix it: Tighten the air connections, soap the connection and recheck system for leaks. To check the dryer outlet valve, clean the valve seat and replace the check valve. To troubleshoot the compressor, either reduce the air demand or switch to a compressor with greater output.

4. The Safety Valve is Open

Causes: The desiccant cartridge may be unplugged, there may be ice blocking the dryer, or the system may be experiencing excessive pressure.

How to fix it: To resolve an unplugged desiccant cartridge, this may be due to excessive oil passage from the compressor. Check for wear in the compressor and replace the desiccant cartridge. For ice blocking the dryer, check the heater function. To resolve excessive system pressure, repair or replace the governor.

5. Short Life of Dryer or Desiccant Cartridge

Causes: The air at inlet may exceed 175 degrees F or the duty cycle of the compressor is not allowing for sufficient time for desiccant regeneration.

How to fix it: See Haldex's installation guidelines for extending the length of the compressor discharge line. Achieving a 175 degree dryer inlet temp can typically be accomplished with 12-15 feet of compressor discharge line. To adjust the compressor duty cycle, keep in mind that during normal operation, the compressor must remain unloaded for a minimum of 30 seconds. This allows time for sufficient purge, and lengthy loading times should always be avoided. The air dryer must be "by-passed" in applications with high air use, such as bulk unloading.

6. Poor Drying Efficiency

Causes: For poor drying efficiency, the air at the dryer inlet may be exceeding 175 degrees F.

How to fix it: For extending the length of the compressor discharge line, see Haldex's installation guidelines for the PURest air dryer. Achieving a 175 degree dryer inlet temp can typically be accomplished with 12-15 feet of compressor discharge line.

Need to Upgrade or Repair Your Air Dryer?

If you need to retro-fit your current air dryer, the Haldex PURest's universal mounting bracket eases retro-fit installations for Pure Air Plus, DRYest, AD type and SS type air dryer bolt patterns.

Whether you need to upgrade your current air dryer or fix the one you have, our full haul of heavy-duty everything has everything you need to optimize your air system – and your uptime – all year long.