Problem: Heater Will Not Operate. EE8 Code Displayed.
Rural Energy Enterprises, Inc. does not accept liability for the improper use of this information. Installation, service, and maintenance of heating equipment should be performed by a qualified technician. Improper installation, adjustment, alteration, service, or maintenance can cause property damage, personal injury, or loss of life.
Applies to: Toyostove Laser 30, 56, and 73.
What Does This Mean?
The EE8 error code is very precise and is only displayed when the circuit board detects a problem with the combustion blower motor assembly. The blower motor assembly is the device that supplies fresh air to the burner and blows the exhaust gases out of the heater. On the Toyostove Laser 56, 60 and 73 the blower motor is a box inside the heater that contains two fans and a motor. One fan pulls fresh air into the heater and the other fan draws the exhaust through the heat exchanger and pushes it outside through the flue pipe. The Toyostove Laser 30 and Oil Miser 22/23 does not have a blower assembly box. The small blower fan motor is mounted on the back of the heater inside a cover and draws fresh air into the heater and then pushes the exhaust through the burner and out of the flue pipe.
What Can Cause An EE8 Error?
Several problems can cause the EE8 error.
- Stuck blower fan. The motor is not spinning at all or not fast enough.
- Inverter output is not compatible with main circuit board electronics.
- Defective motor. The motor is not working. Usually an open fuse inside the motor.
- Loose or defective wiring. The wires that connect the motor to the circuit board are loose or damaged. Circuit board does not get signal from the functioning motor.
- Defective motor sensor or sending unit. The device that sends a signal to the circuit board is not working properly. This part cannot be purchased. It is on all new motors.
- Defective circuit board. Circuit board is not activating the motor or not sensing that the motor is working properly. See Service Manual for voltage and resistance readings
What Can Be Done To Correct This Situation?
- Is the fan stuck? Remove the front cover. Turn on the heater. Listen for a noise coming from the blower. It should start at medium speed and then slow down but keep operating. If you do not hear the motor, it is probably be stuck or not operating. Turn the heater off. On the Toyostove Laser 56 and 73 remove the black rubber elbow that connects the blower assembly with the base of the heater. Turn the heater on again. Look into the outlet hole on the blower. The intake air fan is visible and air should come out of the opening if the motor is operating. If not, turn the unit off and use a tool or finger to try to spin the motor. If it spins freely, proceed to #2.
If it does not spin freely, the motor is stuck or the bearings are seized. In either case, the blower assembly must be cleaned, repaired, or replaced. Before removing the motor assembly, remove the upper panels and the heat exchanger. Remove the top of the blower to expose the exhaust fan and exhaust cavity. You may be able to determine whether there is a problem at this point.
You may use a small brush to remove soot and carbon from the fan and exhaust chamber. Or, you may remove the fan and more thoroughly clean the motor. This will require a 7mm socket or small adjustable wrench and a 2mm hex wrench. In order to remove the exhaust fan, the nut on the shaft must be removed as well as the hex set screw on the side of the fan center hub. Be sure to loosen this screw before attempting to remove the fan. Apply a penetrating oil or lubricant to the hub before trying to remove the fan. Then, grasp the HUB of the fan with a tool or your fingers and work the fan off the shaft. DO NOT grasp the outer part of the fan! The fan will bend easily and will not spin smoothly if it is not perfectly round.
Wash the fan in soap and water. Clean the exhaust chamber. If you have a Toyostove Laser 56 model E or F or a Toyostove Laser 73 model H or I, check the bottom of this chamber. If it is pitted or shows signs of corrosion, the motor may be replaced with a newer style blower assembly that has a stainless liner in this chamber.
- Is the motor defective? A safety fuse is installed in the electric combustion motor on all Laser heaters. On models produced before 1997 this fuse is a non-resetting, one-time fuse. The fuse opens if the motor becomes too hot. Excessive heat is usually a result of extended operation of the heater with low voltage (brownout). This problem may also be caused by low power output from battery/inverter powered heaters. Newer model heaters have self-resetting fuses that will re-close after a short period of time. The heater will stop, display the EE8, but may be able to be re-started if proper power is available and the motor has cooled sufficiently. If this problem occurs often, there may be a problem with the power supply system. This should be corrected to protect the heater and other electric devices.
To verify that the motor itself is defective, apply 120 v AC power directly to the motor or check the continuity of the motor with a test instrument. If no testing tools are available, remove the blower connecting wires from the circuit board (plug G) and connect the motor to the igniter position (Plug H). Turn on the heater. If the motor activates, turn off the heater and proceed to #3. If it does not activate, the motor is defective and must be replaced.
- Is the wiring loose or defective? Two sets of wires connect the blower assembly and the main circuit board. The two larger gray wires supply power from the board. The motor will not spin if these wires are not properly connected to the board and the motor. The three red, white, and blue wires transmit the signal from the motor speed sensor to the circuit board. If the motor is spinning but an EE8 code is displayed, the wires may be loose or defective. Check the wires to be sure they are tightly connected to both the sensor and the circuit board. The motor assembly must be taken out of the heater and the base removed. Remove the two screws in front of the blower and remove any connections from the back of the heater. Then lift the motor out and remove the base plate. The wires will be clearly visible. It may also be necessary to check the continuity of the wires to be sure that the plastic connections on both ends are working.
- Is the sensor working properly? If the motor spins when it is activated but an EE8 code is displayed, it is possible that the sensor on the bottom of the blower motor is not working properly. Remove the blower as described in #3 and remove the sensor. It may be possible to unscrew and replace only the outer part of the sensor but it may also be necessary to remove the round magnet from the bottom of the motor shaft. These parts are not available. The sending unit is on all new motors.
- Is the circuit board defective? Check the main circuit board to be sure power is going to the blower assembly. Check power output on connection C. See service manual for correct voltage. If no power is detected while the heater is on and set temperature is above room temperature, replace the main circuit board. Be sure to disconnect the heater before removing the old one and when installing a new one. Be VERY CAREFUL to connect all wires to their proper position. Note that each wire connector has a corresponding connection on the circuit board. Many connectors are the same and can easily be incorrectly connected. Be very careful about this task!
If voltage is correct at blower motor plug, check Revolution Sensor voltage. See service manual for correct voltages.