dust blower on my dewalt circular saw doesn't work at all, just fills my cut line with sawdust.

Diagnosis

The dust blower on the DeWalt DCS570B is not a powered blower with its own motor; rather, it is a passive pneumatic system that leverages the high-velocity airflow generated by the primary motor cooling fan. As the motor spins, it forces air through a dedicated internal channel that terminates at a small exit nozzle located just ahead of the lower blade guard. When this system fails, it is almost always due to "packing"—a phenomenon where fine sawdust mixes with resin or moisture from the lumber, creating a hardened plug of debris within the narrow air channel. Because the air pressure from the motor fan is relatively low compared to a dedicated compressor, even a small amount of compacted sawdust can completely block the flow. You can confirm this by running the saw at full speed and placing your finger over the blower exit port; if you feel zero air pressure or only a faint flicker of air, the internal channel is obstructed. In some cases, the flexible rubber boot that connects the motor housing to the blower nozzle has slipped or become pinched during a guard adjustment, cutting off the air supply entirely.

How to Fix It

To restore the airflow to your cut line, you must clear the blockage from the inside out and ensure the air path is unobstructed. Follow these exact steps:

1. Remove the 20V Max battery immediately to ensure the tool cannot be accidentally triggered during cleaning.
2. Locate the blower exit nozzle, which is the small circular aperture situated on the front of the tool, just above the lower blade guard assembly.
3. Take a heavy-duty straightened paperclip or a 1/16-inch steel probe. Carefully insert the probe into the blower hole and rotate it vigorously to break up the compacted "cake" of sawdust. Do not push too hard, as you don't want to puncture the internal rubber ducting.
4. Using a high-pressure compressed air canister or a shop compressor nozzle, blow air directly into the blower exit port. This "back-flushing" technique pushes the debris back toward the motor housing where it can be easily shaken out.
5. Turn the saw over and locate the motor intake vents on the side of the housing. Blow compressed air through these vents to clear any remaining residue from the fan blades.
6. Reinstall the battery and perform a test run. The air should now be blowing a steady stream across the base plate and the cut line.

If That Didn't Work

• Check the rubber transition boot. Remove the two screws holding the lower blade guard and inspect the black rubber hose that leads from the motor to the blower nozzle. If the hose is pinched, kinked, or has slipped off the plastic nipple, the air will leak into the tool body instead of reaching the nozzle. Reposition the hose and secure it with a small zip-tie if the original tension is lost.
• Inspect the motor fan for "clogging." If you have been cutting extremely resinous wood (like pressure-treated pine), the fan blades themselves may be coated in a thick layer of sap, reducing the CFM (cubic feet per minute) of air being moved. Use a vacuum with a narrow crevice tool to suck out as much debris as possible from the motor vents.
• Verify the blade guard alignment. If the lower guard has been bent or modified, it may be physically blocking the blower nozzle's path. Ensure the guard drops freely and that the nozzle has a clear line of sight to the wood surface.
• Check for internal housing leaks. If the tool was dropped, the plastic casing may have a hairline crack near the blower channel. If air is escaping through a crack in the housing, it will never reach the nozzle. Seal any visible cracks with a small amount of high-temp epoxy.

Heads Up

• Avoid using the saw in extremely humid or damp environments, as moisture turns sawdust into a cement-like paste that permanently clogs the blower channel.
• Perform a "blow-out" with compressed air every 10-15 cuts when working with softwoods or MDF, as these materials produce the finest dust that is most likely to cause blockages.
• Never use a metal drill bit to clear the blower hole, as you risk drilling straight through the internal rubber seals, which will permanently kill the suction.
• Keep the motor intake vents clear of tape or stickers, as restricting the intake air will not only kill the blower but will cause the motor to overheat and trigger the thermal shutdown.