Your Volvo truck was engineered and built to deliver dependability and industry-leading safety along with every load you haul. In order to keep your truck's integrated system of components performing together seamlessly, it's important to ensure all of your parts support your intended use.

When it comes to your air compressor, one size does not always fit all. The compressor fills the air tanks so you can rely on your brakes to bring your truck to a stop as needed depending on its application. If the use of your truck changes over time, you may need to upgrade your compressor. Here are three signs your compressor may not be the correct size:

  • A duty cycle - or the ratio of time the compressor takes to build air to the total engine running time - of greater than 25%.
  • Your air brake charging system seems slow to build pressure.
  • Excess oil in your truck's supply tank. Air is heated as it's compressed, and cools as it travels through the discharge line to the air tank. The condensation from this cooling creates pools of water in the bottom of your truck's supply, or “wet” tank, which needs to be drained daily. If you notice excess oil and moisture in this tank, even after the daily drain, you may need a larger compressor.

Excess oil in your wet tank can lead to downtime and CSA violations if it is allowed to congeal with moisture and dirt in your compressor. Oil-deteriorated valves and seals will cause the compressor to run more frequently, accelerating failure, and air system leaks can spring from oil-damaged seals, costing you points during roadside inspections.

With proper preventive maintenance and equipment, your air system has multiple components in place to remove contaminants and keep running smoothly while you're on the road. Your truck's compressor has a filter at its outlet, and any contaminants the filter doesn't grab are typically caught by a condenser/separator and then an air dryer. Volvo's exacting specifications require your air dryer to have a coalescing filter that collects oil droplets and a desiccant bed that removes 95 percent of the remaining water vapor from the pressurized air.

The compressor might be the key component of your air brake system, but it isn't always at fault if the system is losing air pressure. If you believe your compressor is the correct size for your truck's application and you're still having problems, try these eight steps:

  • Using shop air, pressurize the unloader line to 120 psi and check for leaks in the line.
  • Remove the air pressure and ensure the unloader line is properly sealed in the governor fitting, then use shop air to check the line again for leaks.
  • Inspect the adapters at both ends of the intake hose for damage.
  • Inspect the intake hose clamps and tighten if needed.
  • Inspect the intake hose for signs of drying, cracking, chafing and ruptures; replace if necessary.
  • Ensure all metal tubes are tight to the mating fitting.
  • Inspect all metal tubes for cracks or breaks and replace if necessary.
  • Check the compressor's exterior for signs of leakage (oil or air), referring to the service data sheet or manual for appropriate tests and corrective action.

When you need to schedule an appointment to get your air system checked out and your compressor potentially replaced, talk to the expert technicians at your local Volvo Trucks dealership to help determine which compressor is best for you, and be sure to have your air system professionally inspected during each preventive maintenance visit. For convenience, quick delivery and regular specials, order air system components online through SELECT Part Store™.

Volvo Brake Compressors