An oven thermostat is a switch that opens and closes in response to the temperature it senses. It is typically found in the control panel, where a liquid-filled temperature-sensing bulb senses and maintains the internal oven temperature by cycling heat on and off.
Before repairs or testing can begin you must disconnect the electricity at the fuse panel, at the circuit breaker panel, or by pulling the plug. Make sure the power is off before proceeding. A jolt from 220 volts can be fatal, use caution!
- Access the oven thermostat, which is located in different places depending on the make and model: On freestanding ranges, access the thermostat by removing the screws that hold the back panel in place at both ends.On models with front-loading controls, remove the panel and tilt it for access. Be careful not to let the wires disconnect from their components. Some built-in models have a removable back splash. Lift the backsplash, rest it on the cook top and remove the screws from the back splash, which holds the rear panel. On wall ovens or eye-level ranges, access the control panel by opening the door and removing the screws that secure it. The screws may be under the exhaust hood or below the control panel. If the control panel is hinged, simply tilt it towards you. On some models both the rear and front control panels must be removed. The screws may be found on the trim and occasionally the trim must be removed.
- When testing the thermostat switch contacts for continuity, refer to the wiring diagram and remove only those wires being tested - and only one pair at a time. Test switch contact terminals as per your wiring diagram. If the switch lacks continuity at any of the contact terminal points then the entire thermostat switch needs to be replaced.
- Adjusting the thermostat: Test the oven temperature by placing the tester in the oven's center and leaving it for 30 minutes at 350 degrees. Record the minimum and maximum temperatures of three cycles, then add those figures together, divide the result by six and you have the oven's average temperature. If the average temperature is more than 25 degrees off, try calibrating the thermostat by following your appliance manual instructions for thermostat calibration. Normally, thermostats are calibrated by pulling the oven's thermostat knob off, turning the knob over and adjusting the calibration ring on the back. If your oven doesn't have a calibration ring you may need to replace the thermostat.
- To remove the thermostat: Disconnect the capillary tube and push it through the back oven wall, being careful not to break the flammable capillary tube wire.
- Remove the screws that secure the thermostat to the control panel and gently pull the thermostat out, leaving the wires in place.
- To install a new thermostat, reverse the disassembly procedure, transferring the wires individually from the old unit to the new.
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