Model #KEBC278KBS0, the bottom oven of this double wall oven setup was working just fine, but the upper oven appeared to not be holding temperature. The customer noticed this while baking cookies that still weren't done when the timer signaled the end of the cycle. The inside temperature was noticeably cooler than expected and the only way to get the remaining batches done was to start the cycle over again.



Ovens work by a simple process of turning on elements until the selected temperature is reached, then turn them off until a minimum temperature has been reached, and then start the cycle over again. Depending on the control mechanism used in the oven, this process is either carried out by a mechanical thermostat or and electronic board along with a temperature sensing probe in the oven cavity. Either way, everything is done by one of these devices.

This particular oven not only has bake and broil elements, but also a convection element used during convection cooking. The bake element is hidden, meaning it is located under the oven cavity to protect it from spills and to provide more even heating. Because the complaint was not holding temperature, I went right to the control board to start my troubleshooting.

Each of the elements is turned on and off by a set of relays on the control board. The electronics use these relays as switches to cycle each element to obtain quick and efficient heating of the oven. From this location, it is easy to check the electrical stability of each element simply by doing a resistance check. In doing so, I found each element to be a complete circuit except the convection element.

During my initial questioning of the customer, I found out the problem only occurred during convention cooking with is really the reason I started checking each element. The reason everything seemed OK to the customer was during preheat, each of the elements is turned on and off to heat the oven cavity, then once the set temperature has been reached, the convection element will be used to maintain the temperature. Because the element had failed, the oven would finish the preheating, then simply cool down during the rest of the convection bake cycle.

I removed the fan cover from the back of the oven cavity exposing the fan and the convection element. Here I found one of the terminals and wires missing behind the back wall, most likely due to a failure at this point. I was able to fish out the missing wire and replaced the convection element. With the cover back in place, a heating cycle was again started to ensure the element would heat, which it did. The oven was again ready for convection baking.

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