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How to Adjust the Thermostat Set Screw

A thermostat set screw is a control device inside the temperature regulating unit which allows the user to determine the minimum or maximum amount of heat or conditioned air to be delivered through the vents. It is a regulator that can limit the volume of cool or warm air. Set screws are found in air conditioning and heating thermostats and refrigerators. Adjusting the set screw is a fairly simple task.

  1. Turn off the air conditioning/heating unit, then open or turn off the breaker at the main power panel so that no electricity is flowing and phantom or latent power is present.

  2. Gently pry the cover off the thermostat using a flathead screwdriver.

  3. Locate the set screw using a flashlight. It will be a Phillips screw or Allen screw.

  4. Turn the set screw to the desired position using a Phillips screwdriver or Allen wrench. Models vary, but in general, a clockwise turn will deliver more volume, while a counterclockwise turn will deliver less volume.

  5. Reattach the thermostat cover and close or turn on the breaker on the main panel. Turn the air conditioning/heating unit back on and test it for volume delivery.