Bunn-O-Matic RL35 Troubleshooting

The Bunn-O-Matic RL35 is a commercial-use coffee brewing machine. The RL35 is commonly used in restaurants or convenience stores. This stainless steel coffee maker features a safety splash guard and five separately controlled warmers, and it brews 7.5 gallons per hour. The Bunn RL35 is a fairly durable coffee maker, but problems can occur over time. It will take about 30 minutes to an hour to troubleshoot and repair most problems with the Bunn RL35.

Things You'll Need

• Phillips screwdriver
• Multimeter
• Replacement solenoid valve (possible)
• Replacement control thermostat (possible)
• Replacement limit thermostat (possible)

Instructions

Check the Solenoid Valve

1. Test the solenoid valve if the Bunn makes unusual noises or if water flows into the fill basin continuously when the brew station warmer switch is turned off.

2. Remove the top cover of the Bunn with a Phillips screwdriver. Set the multimeter to the voltage setting and place the positive test lead on the blue wire and the negative test lead on the black wire. Voltage across the wires should be 120 volts. If it is not, or if you do not hear a clicking when the warmer switch is activated, the solenoid valve needs to be replaced.

3. Disconnect the machine from the electrical outlet. Unhook the electrical wires and the water lines attached to the old solenoid valve with the screwdriver. Remove the valve retaining screws and lift the old valve out. Insert the new solenoid valve and replace the retaining screws, reconnect the water and electrical wires, and then replace the cover.

Check the Control Thermostat

1. Check the control thermostat if water coming out of the maker is not hot or if the machine spits or steams.

2. Remove the top cover's retaining screws and top panel to access the control thermostat.

3. Unplug the coffee maker and test the voltage running across the blue and red wires with the multimeter by placing the positive meter lead to the red lead and the negative meter lead to the blue wire. The voltage should be 120 volts. If it is not, replace the control thermostat.

4. Remove the control thermostat wires with the screwdriver. Pull up on the capillary tube at the top of the tank lid to remove the thermostat bulb. Remove the thermostat retaining screws, take the old control thermostat out, and mount the new one. Slip the bulb and capillary tube through the grommet by hand until it is seated securely.

Check the Limit Thermostat

1. Check the limit thermostat if water coming out of the maker is not hot or if the machine spits or steams, and you've determined that the control thermostat is not the problem.

2. Unplug the machine and remove the back panel with the Phillips screwdriver to access the limit thermostat.

3. Use the continuity test function on the multimeter to test the continuity across the limit thermostat terminals. If there is no continuity replace the limit thermostat.

4. Remove the wire ends from the thermostat and then slide the thermostat from under the retaining clip. Slip the new thermostat under the clip and connect the wire ends.

Tips & Warnings

• Check the electrical connection if the coffee maker will not power up. Look first to see if the Bunn is plugged in. If it is, unplug it and plug another appliance in to make sure the outlet is working. If the outlet is bad, check the circuit breaker and flip the breaker if it is in the off position.

• Check the siphon system tubes connected to the back of the Bunn if the water does not flow properly. Clear out any obstructions from the siphon tube with a thin piece of wire.

References

• Bunn RL Operating and Servicing Manual