, the topic for this post comes from the mailbag and is very timely given the upcoming Thanksgiving holiday. Commenting on a recent post
, Kurt had this to say.
Wow - I had the same problem last year and replaced the TOD which fixed the problem. (Kitchen Aid Double Oven - Model #KEBS208DSS11) Last week, during the self-cleaning cycle the oven lost power. I once again placed the TOD (which was blown), but I still have no power. There is power to the oven, and I believe power from the transformer to the panel, but no response from the panel. Any ideas?
A couple things come to mind, but more importantly, I bet I have the solution.
As Kurt already knows from personal experience, and as I posted about, most built in ovens along with many newer free standing ovens have some form of thermal protection. The purpose of this protection is to prevent an overheating condition and the possibility of a fire in the event a heating element control circuit became stuck in the on position. If this were to occur, the oven cavity temperature would continue to increase until something possibly catastrophic caused the element to shut off. To ensure our ovens operate in a safe manor, thermal protection, often called thermal overload devices (TOD's), are employed in the electrical circuit to shut off power to the elements when they are subjected to an over temperature condition. The use of these devices overall is a good thing to protect our appliance and home, but it is possible for a failure to occur by accident resulting in our oven no longer heating. The most likely cause of this kind of failure is the use of the self clean cycle.
During the self clean cycle, the interior temperature of the oven reaches in excess of 700 degrees and essentially becomes an incinerator turning remaining food items or spill over into ash. This high temperature can also cause the outside of the oven to heat enough to cause the TOD to open the circuit to the heating element. Contributing factors can be slow running cooling fans, improper airspace around the unit for ventilation, and poorly sealing doors. But all to often the TOD will open simply because of age. As they are subjected to high temperatures time and again, they become weak and are more likely to trip at a lower temperature. But enough with theory, lets get back to Kurt's problem.
As he mentioned, he has had experience replacing TOD's after self clean, and indeed found one of the two on his oven had tripped. But after replacing the failed component, the oven still didn't work. Most likely the reason for this is his oven has a third TOD mounted behind the control panel that when subjected to excessive heat, will open the circuit to the control panel transformer. When this one opens up, the display goes out and nothing will work. Looking more like a resistor or diode, this axial thermal fuse works on the same principal as any other TOD, it's just in a different wrapper. By replacing the thermal fuse, I am sure Kurt will have his oven ready for Thanksgiving cooking.