Bunn Commercial Coffee Maker Troubleshooting: Bunn Coffee Maker Problems Explained

A dose of caffeine is a must for morning sleepyheads, night workers, or those who just have pure love for coffee. Coffee makers are these people’s trusty sidekick to ensure that they have their favorite drink ready when they need it.

The efficiency of this machine saves you time and energy in brewing your coffee, and you get a perfect cup every time.

However, just like any other appliance, there is a tendency for a coffee maker to face some unpredicted problems. It might stop functioning at one point, and it’s not dispensing the coffee well.

There’s no need to worry about this, and you certainly don’t have to spend a cent to buy another one or pay someone to fix it.

Experience is not an issue if you read this guide, where all the possible issues in your Bunn Coffee Maker are listed and how to fix them. Try these troubleshooting suggestions, and be back on track in brewing your cup of coffee!

bunn cappuccino machine troubleshooting

Common Bunn Machine Coffee Problems

If you are facing common problems with your coffee machine that can be found below, you can try correcting them by yourself.

The troubleshooting guide provided will let you know what you might have been doing wrong that causes the problems. Under the problems listed, check all the solutions to find and fix the root cause of your coffee maker’s defect.

1: Liquid-related problems

1.  Overflowing or leaking water

Your brewing vessel should be empty. Check under the funnel for the server, and make sure that it’s empty. If you’re starting a new brewing cycle with leftover coffee, it will likely be the cause of why it is overflowing.

The brew volume adjustment should be set at the right setting. If the level is set too high, then it will overflow. To know the correct settings for your coffee maker, check the user manual that comes with the machine.

Check the spray head. Your spray head might be missing or damaged, so you should replace it with another one. In other cases, your spray head might just need a recalibration to adjust the brew volume.

Try another coffee grind or filter paper. Firstly, run a brew cycle with no filter or coffee grinds. If it overflows, then the problem is not about the two said components. However, if it doesn’t overflow, use another filter paper or coffee grind.

Sometimes, choosing the wrong paper filter or a finely ground coffee grind causes this problem. A Bunn paper filter is recommended to ensure that you are using the appropriate filter for the job.

Clean and de-lime. Instructions on how to clean and de-lime the machine can be found in the last section.

2.  The fill-time of the water tank is longer than normal

The water supply line should always be clean. Water will have a hard time passing through the supply line if waste is stuck in it. Make sure to keep your supply line regularly cleaned, or if it’s already too worn out, replace it.

The solenoid valve or control board is damaged. If the above solution is not the cause of your problem, you will need a technician to look at these two parts.

2: Temperature problems

Heating issues in your machine may be caused by incorrect use or damage that is connected to electrical wires. If you are dealing with the latter and you are not in any way knowledgeable about electrical appliances, it is better if you contact a technician.

Check the user manual. There are different Bunn models, thus you have to personally check on the provided user manual to know what is going on. If you have a digital display that shows the error message, it should tell you the problem.

Your brewer is not yet heated. A simple cause to this problem is that you are not waiting for the machine to get properly heated to the right temperature.

There is a problem with the electrical parts which needs technician help. Some parts that can cause this problem are the tank heater, tank heater switch, control board, limit thermostat, thermal fuses, and probes. These can’t be solved alone if you do not have any skills or tools for the repair. Dealing with electrical wires is dangerous, thus it’s highly recommended to contact a trusted technician.

3: Structure-related problems

A coffee maker’s parts can be completely fine, but they can still not work properly due to external factors or placement. Vibration is normal especially for automatic machines, but if it oddly appeared, it should be fixed.

bunn commercial coffee maker troubleshooting

1.  The machine is not brewing the coffee

Check the coffee maker’s water supply. Check the water lines to see if water is entering here. If it’s not, there might be a leak or obstruction in the lines. Also check the shut-off valve, as it cuts off the water supply if it’s turned off.

2.  The machine is not starting

There must be a power supply. Any electrical appliance should be connected to a power supply, so check if it is plugged in the socket or not. If it is, check the power supply switch if it’s turned on.

There must be a correct voltage output. Your power supply and the required voltage of your Bunn machine may not be compatible. It is best to contact a technician about this problem.

3.  Noise and vibrations are coming from the machine

Check the water or plumbing lines and the inlet solenoid. Adjust the pipes away from countertops, as the direct contact form of the two creates noise and vibration.

Inlet solenoids should not be loose. Simply tighten the screws to the right fit.

Check the tank heaters. This part of the machine is highly crucial for it to work. If this is vibrating, you need a technician.

Clean and delime. Instructions on how to clean and de-lime the machine can be found in the last section.

4: Weak beverage taste

To make coffee, you need a combination of hot water and coffee grinds. Both should be at their proper temperature or amount. If one is not working its job, then your coffee would taste bland.

The filter paper should be correctly placed on the funnel. You have to make sure that the filter is not bent and covers the whole brew basket. The coffee grounds should also be even at the bottom for the coffee to be extracted properly.

how to operate a bunn coffee maker

Make sure that the water temperature is not too low. The coffee maker should be set higher than 195 degrees Fahrenheit, as anything below this is not suitable for the extraction.

Sprayhead should be working properly. Check for any damages or obstructions in the spray head. This greatly affects the quality of the coffee as the blockage can prevent the even distribution of water.

Try another coffee grind or filter paper. Test out combinations of coffee grinds and filter paper, as these two need to work flawlessly with one another for a pleasing beverage. The filter paper might drain water too fast to extract the flavors, or the coffee might not be enough for the extraction. Bunn coffee makers always work on top of their game, and it is up to you what products you will use in it.

5: Steam-related problems

Spitting steam or too much steam from your Bunn means that you do not clean or de-lime it regularly. The abnormal steam production is caused by lime buildup, which hinders the temperature sensing of the coffee maker.

Keep it clean and de-limed to avoid malfunctions and other problems! The maintenance guide to your Bunn Coffee Maker can be found in the last section of the article.

6: Bunn Coffee Maker Maintenance

A simple fix to your coffee maker is by cleaning and deliming it. Waste in different parts of your machine may cause more than technical problems.

You will be drinking coffee from the machine, and you don’t want your coffee to be mixed with some waste products from your previous brewing cycles. 

Deep cleaning Instructions

1.  Switch off your coffee maker and unplug it from your power source to disable the electricity in your appliance.

2.  Clean the outside of the machine with water and mild cleaning products. Rinse the soap with a damp cloth, and use another cloth to dry.

3.  Detach and clean the brew funnel by washing and sanitizing it.

4.  Detach and clean the spray head with a mild cleaning product. Be sure to remove all the lime deposits.

5.  Reassemble and repeat two to three times a week.

Deliming Instructions

The lime buildup is the main trouble of a coffee maker and it may even cause permanent damage to some parts of a coffee maker if it’s not properly cleaned. Deliming tools and deliming spring are used for the deliming process.

1.  Insert the deliming spring in the spray head tube while sawing back and forth to loosen up the lime deposits.

2.  Fill the reservoir with a de-scaler, made with distilled water and vinegar in a 2:1 ratio. Start a brew cycle and dispose of it when the process is done.

3.  Detach and clean the spray head, making sure that there are no leftover lime deposits. Reattach when you’re done.

4.  With a distilled water, start another brew cycle to remove odors from the de-scaler. Repeat this until the odor and flavor are completely gone.


Coffee makers are a crucial part of the day-to-day life of a caffeine buff. Without this working properly to get the coffee brewing, there would be a hindrance to the productivity of its user.

However, you don’t need to worry much as it can usually be fixed with the help of your user manual guide or this online post. As long as you know what problem your coffee maker is currently facing, you can easily troubleshoot and fix this. Nevertheless, there are still limits to how much you can work around these coffee machines.

Do not hesitate to contact a technician if you are facing a bigger difficulty than what is tackled above. Not only will there be a chance for you permanently damage your coffee maker, but you might also zap yourself from the electricity.

A technician for your coffee maker is surely less expensive than a hospital bill!

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About David Dewitt

Hi, my name is David and I come from Columbus, Ohio. I am a amateur photographer, and a coffee lover. I love to write, and don't mind me a cup of joe!