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Updated: Jun 11

Step-by-Step Guide to Adjusting the Pressure Switch

Tools and Materials Needed:

  • Screwdriver (usually flathead or Phillips, depending on the switch)

  • User manual for your specific air compressor model

  • Safety gloves and goggles


  1. Safety First:

  • Turn Off the Compressor: Ensure the air compressor is turned off and unplugged from the power source.

  • Release Air Pressure: Release any stored air pressure in the tank by pulling the safety valve or using the drain valve. This prevents accidental release of air during adjustments.

  1. Access the Pressure Switch:

  • Locate the Switch: The pressure switch is typically found near the motor or on the tank. It is usually a small box with electrical connections and a cover.

  • Remove the Cover: Use a screwdriver to remove the cover of the pressure switch. Inside, you’ll see the adjustment screws and the wiring.

  1. Understand the Adjustment Screws:

  • Main Cut-In/Cut-Out Screw: This screw adjusts both the cut-in (when the compressor turns on) and cut-out (when the compressor turns off) pressures. Turning this screw clockwise generally increases both pressures, while turning it counterclockwise decreases them.

  • Differential Screw (if available): This screw adjusts the difference between the cut-in and cut-out pressures. It allows fine-tuning of the pressure range. Not all pressure switches have this feature.

  1. Make Adjustments:

  • Determine Desired Pressure Settings: Refer to the user manual for the recommended pressure settings for your specific compressor model. Typical settings might be around 90 PSI cut-in and 120 PSI cut-out, but this varies by model.

  • Adjust Cut-In/Cut-Out Pressures: Turn the main adjustment screw to set the desired pressures. Use small increments and test frequently to avoid over-adjustment.

  • Increase Pressure: Turn the screw clockwise.

  • Decrease Pressure: Turn the screw counterclockwise.

  • Adjust Differential (if applicable): Adjust the differential screw to fine-tune the pressure range.

  1. Test the Settings:

  • Restore Power and Test: Plug the compressor back in and turn it on. Allow the compressor to run and observe the pressure gauge.

  • Verify Cut-In and Cut-Out: Ensure the compressor turns on and off at the desired pressure settings. If not, make further adjustments as needed.

  1. Secure the Cover:

  • Once the pressure settings are correct, replace the cover on the pressure switch and secure it with the screws.

  1. Final Checks:

  • Ensure all connections are tight and there are no leaks. Monitor the compressor’s operation for a few cycles to confirm the settings are stable.

Important Tips:

  • Refer to the User Manual: Always refer to the user manual for specific instructions and recommended settings for your air compressor model.

  • Make Small Adjustments: Make small incremental adjustments to avoid drastic changes in pressure settings.

  • Safety Precautions: Always follow safety precautions to prevent accidents. Wear safety gloves and goggles when working with pressurized equipment.

Need Help?

If you encounter any difficulties or need replacement parts, such as pressure switches, H&K is a reliable source for air compressor parts and support. Contact them at:

H&K Air Compressors

  • Phone: 214-428-2868

  • Website: Visit their website for more information and to explore their extensive inventory of air compressor parts.

By following these steps and ensuring regular maintenance, you can keep your air compressor operating efficiently and safely. Adjusting the pressure switch correctly is crucial for optimal performance and longevity of your compressor.

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