A Bunn coffee maker boils water and then drips it through coffee grounds to make coffee. This coffee then drips into a decanter which is kept warm through insulation or a heating element in the coffee maker base. If the coffee is not coming out, if the funnel is overflowing, or if water flow begins before the lid is closed, you may have a problem that you can troubleshoot yourself. Problems include improper setup, improperly ground coffee, or a clogged funnel or sprayhead. Additionally, your Bunn coffee maker may require deliming.
Coffee Is Not Coming Out
Perform the initial setup on the coffee maker. Make sure the coffee maker is not plugged in. Slide the empty funnel into the funnel guides, fill the decanter with cold water, open the lid and pour water from the decanter into the brewer, put the decanter back on the base, then close the lid and wait three minutes for the internal tank to partially fill. Open the lid, fill the decanter with cold water again, and once more pour the water directly into the brewer. Put the decanter back on the base and wait for water to flow out of the funnel and into the decanter. Once it has stopped flowing, pour out any water that is in the decanted and plug in the coffee maker. Press the on switch to turn the coffee maker on and heat up the water in the tank.
Ensure the lid is completely closed. If the lid is open, the Bunn coffee maker will not brew coffee.
Check the see how much water is in the water tank. The Bunn coffee maker will not begin brewing coffee if less than 20 ounces (4 cups) of water is present in the water reservoir tank.
Delime the coffee maker. Unplug the coffee brewer and allow it to cool down. Remove the sprayhead by turning it by hand and set it aside. Insert the flexible deliming tool into the sprayhead tube until all but two inches are showing. You may need to twist and force the tool to go in. Slide the tool in and out several times to loosen lime buildup. Check the sprayhead for lime buildup. If there are flakes of minerals, they can be removed with a toothpick. Scrub the sprayhead with soap and water. Rinse the sprayhead with water and replace it in the coffee maker. Pour water into the water tank and turn the coffee maker on, allowing water to run through without making any coffee. This will flush any lime fragments through the system. Empty the decanter.
Decanter Fills Only Part Way
Perform the initial setup described in Step 1 of the previous section.
Check to be sure that evaporation has not occurred. As the coffee is heated from below, evaporation will occur at a faster rate than if the coffee were allowed to cool.
Adjust the amount of water put into the coffee maker. Some water will be absorbed into the coffee grounds, so add more water to the tank to compensate.
Funnel Is Overflowing
Use Bunn brand coffee filters. If the coffee filters you are using do not allow water to go through the filter fast enough, this may cause a funnel overflow. Bunn brand coffee filters are designed to allow the right amount of water to pass through at the proper rate.
Check to be sure the sprayhead is not missing or clogged with lime. If the sprayhead is clogged with lime, it can be cleared with a toothpick and scrubbing with soap and water. Be sure to replace the sprayhead after cleaning.
Switch to a coarser grind of coffee. Coffee that is too finely ground may not allow water to pass through quickly enough to avoid overflow.
Water Flow Begins Before Lid Is Closed
Ensure the lid is completely open. If the lid is partially closed, the water flow may begin before you have a chance to fill the water tank completely.
Make sure the water is not flowing from the upper tray. The upper tray is not designed to hold water for long periods of time and may flow out before you can replace the decanter in the coffee maker base.
Remove the top lid completely. Check that the rocker arm is in position and the rubber stopper area has been thoroughly cleaned. If the sensor does not detect that the lid is opened, this may cause premature water flow.