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What To Do When Your Air Compressor Won’t Build Pressure

Nothing about your air compressor seems wrong. It’s not making any weird noises, the engine is running, and the pump sounds like it’s going, but no matter how much your compressor runs, it simply can’t build any air pressure. If this happens to you, there are a few steps you can take before taking it to a professional or replacing your compressor. Here’s what to do when your air compressor won’t build pressure.

Failing Intake Valves

If an intake valve has failed, then it’s likely that your air compressor is only drawing air in on one cycle. This means that any air it takes in is being blown right back out rather than into the air tank. The best way to diagnose this issue is by removing the intake valve and feeling if the air is moving in and out of the opening while the compressor is running—just be careful, the pump may be hot!

If the air is blowing back out of the opening, then the problem may be a defective reed or flapper valve. This will require a trip to a compressor repair shop so that they can deconstruct the compressor and more accurately identify the issue. Once they have, they will source new compressor parts to replace the defective components.

Defective Piston Seal

Air compressors have filters that prevent dust and debris from clogging the airways. They restrict particles from getting into the compressor tank. These filters also include rings that prevent excess oil from flowing into the compressor’s cylinders. When these fail, your pistons can become blocked.

If you suspect this is the case, it’s worth the effort to check both the piston seals and the rings to see if they’ve become worn down or damaged. Such issues can be identified by checking if air or oil is coming out of the oil fill tube. If this is the case, then the air compressor piping and fittings need to be replaced as the seal is no longer firmly attached.

Compromised Tank Check Valve

The check valve is the component responsible for restricting compressed air from backflowing into the pump. When this fails, the discharge head may receive too much air pressure, which prevents the motor from running as well if at all.

If your tank check valve is the issue, then the root of the problem will be air leaks from the unloader. A good way to check for this is to see whether your unloader valve makes a hiss when the compressor reaches its cut-out pressure. If it’s leaking, then your air compressor can’t build air pressure, and you should replace the check valve immediately to prevent further damage to the system.

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