Shop Talk

Gather the necessary tools and supplies: You will need a new air dryer filter, a pair of gloves, and a few basic tools such as a wrench or socket set and a special large filter wrench. Drain the air from the system: It is very important to completely drain all of the air from the truck's system, preferably using the drain valves on the air tank reservoirs and monitoring the air pressure gauges on the dash. Use caution when removing the filter, as the system is normally pressurized and may still be pressurized even after draining. Locate the air dryer: The air dryer is typically located near the front of the vehicle, often on the driver's side. It may be mounted on the frame or on the cab, or it can also be located on the driver's side behind the steer axle near the transmission. Remove the old filter: Depending on the specific make and model of your semi truck, the filter may be held in place by a clamp, bolts, or some other type of fastener. Use the appropriate tool, such as a large filter wrench, to remove the old filter. Inspect the filter and air dryer base: Before installing the new filter, inspect the old filter for oil residue. Also inspect the air dryer base for oil residue, air dryer filter desiccant particles (a sandy or beady substance), or clogged ports. If necessary, the air dryer base may need further repair or cleaning. Install the new filter: Once the old filter has been removed and the air dryer base has been inspected, insert the new filter into place and secure it using the same fasteners that were used to hold the old filter in place. Test the system: Once the new filter has been installed, test the air dryer and the air brake system to make sure everything is working properly.

What are some potential causes for a Volvo VNL to keep purging air? There are several potential issues that can cause a Volvo VNL semi truck's air dryer to keep purging. These include: Faulty air dryer filter: The air dryer filter is responsible for removing moisture and contaminants from the compressed air as it passes through the purge system. If the filter is clogged or otherwise faulty, it may cause the purge system to initiate more frequently. Air leaks in the brake system: If there are air leaks in the brake system, it may cause the pressure in the air tanks to drop, which can trigger the purge system. Faulty air compressor: The air compressor is responsible for generating the compressed air used in the brake system. If the compressor is faulty or not functioning properly, it may cause the purge system to initiate more frequently. Faulty purge valve: The purge valve is responsible for allowing a small amount of air to flow through the air dryer filter during the purge cycle. If the purge valve is faulty or not functioning properly, it may cause the air dryer to initiate the purge more frequently or for longer periods of time than necessary. Faulty turbo cut-off valve: The turbo cut-off is located in the air dryer base as well, along with the purge valve and works in sync with the other valves, if any of the parts inside of the air dryer base are malfunctioning it can cause frequent purges. Faulty air dryer base: The air dryer base is responsible for supporting the air dryer, containing all of the valves, ports, sensors and tubing, connecting it to the brake system. If the base is faulty, clogged or not functioning properly, it may cause the air dryer to initiate the purge more frequently. Faulty or failed air compressor governor: The air compressor governor is responsible for controlling the output of the air compressor. If the governor is faulty or has failed, it may cause the air dryer to initiate the purge more frequently. Blocked or leaking air compressor signal line: The air compressor signal line is usually a small tube that connects the air compressor to the air dryer. If this line is blocked or leaking, it may cause the air dryer to initiate the purge more frequently. Blocked or leaking air compressor discharge hose: The air compressor discharge hose is responsible for carrying compressed air from the compressor to the air dryer. If this hose is blocked or leaking, it may cause the air dryer to initiate the purge more frequently. Air leaks in the suspension system: If there are air leaks in the suspension system, it may cause the pressure in the air tanks to drop, which can trigger the purge system. Air leaks in the transmission system (if applicable): If the Volvo VNL semi truck is equipped with an air-assisted transmission system, there may be air lines that run from the air tanks to the transmission. If these lines are leaking, it may cause the air dryer to initiate the purge more frequently.