Learn how your appliance is supposed to operate so you can determine if it is malfunctioning.
On conventional ranges, the oven temperature is most often controlled by a hydraulic thermostat. That thermostat consists of an electrical switch box mounted in the control panel, a shaft which the temperature adjustment knob attaches onto and a sensor bulb connected to the control body via a capillary tube. The sensor bulb filled with gas is inserted into the oven cavity. As the sensor is heated by the oven air temperature gas from the sensor bulb is forced through the capillary tube to the thermostat body where it actuates electrical contacts which open and close in response. When open the thermostat contacts stop power from getting to the oven elements. When closed power is allowed to feed the elements where they generate heat.
Contrary to popular belief an oven does not maintain an exact temperature. The cycles of heating and not can allow the oven temperature to vary by 20 degrees above and below the set temperature. The result is an average oven temperature that the control is set for.
The sensor bulb of the thermostat is what senses the oven air temperature and allows the thermostat to react to control the on and off cycles of the oven elements. That sensor is held in the oven cavity away from the walls and racks by some sort of clips. If that sensor should come into contact with the oven cavity walls or oven rack, the temperature it senses will be that of the metal they are made from rather than the oven air temperature as it should.
Check to make sure the thermostat sensor bulb has not come loose from those mounting clips and making contact with metal components inside the oven. If it did, erratic oven temperatures could occur. In most cases lower than expected oven temperatures might be experienced with under or uneven cooking the result.
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