Model #CVE3401W, this four burner cook top had a right front element that would only operate on the high setting no matter which position you turned the knob. Because the temperature of each element is selected and controlled by the corresponding infinite switch, I had a pretty good idea where the problem was without even turning a screw.
What's in a Name
Heating elements on ranges, or cook tops are controlled by an infinite switch. These switches, which the control knob attaches to, allow for a temperature selection from low to high, and anywhere in between, thus the infinite portion of the name. Each switch has a set of terminals where the 240vac circuits (L1 and L2) will connect, along with outputs (H1 and H2) to the element connections and a pilot or surface indicator light. Because both electrical circuits pass through the switch, there is no voltage present at the element when the switch is turned to the off position.
Infinite switches control the element temperature by cycling the power on and off to achieve and maintain a set temperature. The hotter the selected temperature, the longer the element will remain powered on (also referred to as the duty cycle). This cycling of the power to the element is controlled by a small heating coil and bi-metal thermostat that are integrated into the infinite switch housing. As current passes through the heater coil and on to the surface element, the heat from the coil will cause the thermostat contacts to warp and open up the electrical connection to the element once the set temperature is reached. With the connection open, the internal heater coil will begin to cool until the thermostat contacts return to the closed position where the cycle begins again.
Because the element on this cook top stayed on no matter the position of the switch, this was a good indication the internal thermostat contacts had become fused together, and a quick continuity check with my meter verified that fact. After removing the switch and making note of all the wire positions, I installed a new infinite switch paying close attention to the wire placement. This element now heats from low to high, and everywhere in between.
Please note: in case you have the same cook top, the right front burner is a duel element and requires a duel infinite switch. The concept of the single and duel infinite switch is the same, it's only the number of wires and their connections that change.