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Please could you help me diagnose this issue and suggest which parts might need replacing?
We have a Zanussi built in DUO ZUA 65. We have problems with the main fan oven.
If we set a temperature on the dial, the oven (say, 180 degs) the bulb next to the dial will light ok to show it is heating up it will get up to temperature ok.
However after a while, the power will be cut to the element and the oven will start cooling down. The bulb next to the dial will remain off, even if you dial in a temperature above the last known set point.
One the oven has cooled down (about 30 minutes) the dial bulb will come on again and the temperature will start rising again as energy is getting to the element.
After being at temperature for a while, it cuts power to the element again and the above cycle continues.
The clock and fan continue to work as normal through this process, even when the element has lost power.
Also, one time i opened the oven door to see the element at the back of the fan oven glowing red hot. I have not seen this before.
Any ideas? Main thermostat? Safety thermostat? Anything else?
Re: Please help diagnose oven fault – cuts out when hot
Could be the safety stat. Trouble is the only way of testing that theory is that you will need to run the oven to the point where it cuts out then check the safety stat (aka TOC).
I must point out that in order to do that the power to the appliance must be isolated FIRST……!!!!
Re: Please help diagnose oven fault – cuts out when hot
I have done a quick test and have the following additional information;
The oven cuts out when it reaches about 190 degsC.
At 190 degrees, the orange bulb by the temperature dial flickers for about a second and makes a quiet “fizzz” noise, then the light, element AND FAN looses all power.
If you turn the temperature dial during this state, you can hear the thermostat click on and off as you turn the dial above and below the current temperature.
I have previously replaced the element a couple of times. i cant remember how long the latest element was in before the problems arose. Could this be caused by a faulty element?
I really need some ideas on this one. Can anyone help?
Re: Please help diagnose oven fault – cuts out when hot
Sounds as if it’s cutting out on the overheat so it will most probably be the main oven thermostat or the overheat that’s the problem and not the element.
K.
Re: Please help diagnose oven fault – cuts out when hot
Just regarding the overheat comments…
I was sat watching the oven during the previous test. I was watching the temperature rise up to190 degrees by using the thermostat to gauge where the temperature was at. I also kept opening the oven door to get a rough idea how “hot” the oven was.
It really wasn’t that hot when it cut out. It’s not like the oven thought it was 190 but it was actually at 250+. Can it experience an “overheat” condition when the true temperature is only 190 degrees?
Could the sensor that detects overheat be at fault? i.e. that sensor through my true 190 was really 250?
Re: Please help diagnose oven fault – cuts out when hot
If you’re not testing it with a thermometer then how do you know what the temperature in the cavity is?
If the main stat is faulty as I think it may be, all that’ll happen is it will heat and heat till the overheat kicks in and shuts it down. The thermostat will not shut the elements off as it should.
The temperature in that scenario is not really relevant.
K
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