Troubleshooting the W-7 Low AMP Warning

The W7 low amps error occurs when an amp draw lower than 25 is detected by an amp sensor(s) for four seconds of continuous heat or longer. The error will not show until nine seconds after there is a demand for heat, as the amp sensors start reading five seconds after heat energizes. This error does not disable the heating system, and cooking can continue. The error can be acknowledged by the user, causing it to disappear, but it will reappear after 30 minutes if low amps are detected again. This error code can also appear after a filtration cycle if low amps are detected.

Error Code Display

• W - 7U: Indicates a low amps condition in the upper heater.

• W - 7L: Indicates a low amps condition in the lower heater.

• W - 7M: Indicates a low amps condition in both heaters.

When the W7 low amps error occurs, the amp draw ratings for the heating element with the issue will be displayed on the screen. The low amp value will be flashing. If the low amp value is flashing on the middle display, this would indicate an issue with the upper heater. If the low amp value is flashing on the lower display, this would indicate an issue with the lower heater. If both middle and upper lines have a flashing value, then there are issues with both heating elements. For a heating element, where the amp draw readings are within range, the display will only show dashes "- - -". When the error is recorded in the error log, only the lowest amp value will be shown next to the W7 code.

For example, " W-7U Heat Amps Too Low, 19 amps"

Call Avoidance

Before scheduling a service call, try the following steps:

1. Check Power Cords: Unplug and reconnect the power cord to ensure there is no low voltage condition.

2. Check Breakers: Verify that the breakers are not tripped. Turn the breaker off and back on to ensure proper contact.

Field Troubleshooting

If call avoidance steps do not resolve the issue, proceed with the following field troubleshooting steps:

Recommended Parts:

• Heating elements

• Contactors

• Amp sensors

• Breaker

• Bus bars

• Control board

• Wire

Recommended Tools:

• Cross tip screwdriver

• Multimeter

• Amp clamp

Troubleshooting the Heating Elements and Amp Sensors

1. Check Error Log and Amp Draw: Look for a low amps W-7 error message. this check may help to narrow down if the issues are isolated to an upper or lower heating element to more quickly pinpoint the fault. You can also see amp readings, 32 amps is nominal.

• If one or more of the readings are 0, check amp sensors first, otherwise continue with step 2.

• Disconnect power from the fryer.

• Lower control panel.

• Disconnect power to control by removing connector P2.

• Unplug amp sensors and check resistance of each sensor.

  • The sensor should be 33 Ohms +/- 10% (Cold Check).

  • If any one of the sensors are outside of this range, replace amp sensor.

2. Check Incoming Voltage: Verify line voltage is present between all three phases at both the incoming side of the primary and secondary contactors for the respective heater for a W-7 U or L error, or all contactors for a W-7 (M) error. If voltage is low or not present, troubleshoot back to the source through the breakers, wiring, terminal block and power cord, receptacle to the breaker at the restaurant side to find faulty component or loose connection. Once found, replace the faulty component, wiring, or resolve voltage issues at the restaurant side.

NOTE: loose connections are sometimes identified by discolored or burnt wire(s). If this situation is found, replace wire and tighten connections (check other connections and tighten to 36 ft-lb. If no fault with voltage, continue to next step.

3. Check Voltage to Heater(s): With power switch turned on and a demand for heat, check voltage between all three phases for each contactor. If reading is low or 0 for any contactor, proceed to step 4, otherwise check amp draw at each heating element wire from top of contactor. There should be 18.5 amps present on all six wires when there is a demand for heat. If your amp draw is 0 or lower than 10% of this on any wire, check connections, if connections are tight, replace respective heater.

4. Check Contactor Coil Voltage: Ensure 24VAC between the blue or yellow wires to the primary contactor coil when the power switch is turned on, if no voltage, ensure control has a demand for heat, check coil wire connections at control and if tight, replace control. Ensure 24VAC between the blue or yellow wires to the secondary contactor coil when there is a demand for heat, if no voltage, ensure control has a demand for heat, check coil wire connections at control and if tight, replace control. If coil voltage is present, contactors pull in, but voltage is low or missing, replace contactor.

Other Possibilities

AMP Sensor Calibration: Place amp clamp onto amp sensor(s). If your reading is +/- 10% of the reading on the control, perform amp calibration