CDA fan element not heating BUT element is good

[menderman]

3 months back I was on here as i needed to replace the round fan element but now it will not heat up.
I tested the element for continuity and its ok but then tested for power with the oven and temp gauge up and I have no power at the element.
The top and bottom oven selections are working ok
At least 5 years ago I had the selector switch replaced as the same element would not work, so as I have just replaced the element then I suspect its the selector switch again.
Interesting I saw a utube advice that to correctly operate the oven you should first turn the selector for the oven part and then turn the thermastat. And turn of by first turning down the stat and so cutting the power to the switch first otherwise you can end up burning out the selector switch.
We 95{e5d1b7155a01ef1f3b9c9968eaba33524ee81600d00d4be2b4d93ac2e58cec2d} of the time use the same round fan element.

I have the old selector switch that was replaced and can see it was burnt with part of the cam melted at the ring element selection setting.
CDA OVEN CD9002/1

[kaibart]

More than likely the switch or wiring to the switch has bad connection

[menderman]

Thanks for your help.
I suppose I need to have a look at the switch and also test the wire from the switch to the element.
One thing though – am I allowed to as it is a duel fuel range cooker with a gas hob and to get to the switch I need to lift off the hobs pressed stainless steel top plate, it fits over the burners although I do not have to touch them.

[electrofix]

its one of those grey areas

i have done it many times. I see it that as long as i dont have to break a gas joint am ok

Dave

[menderman]

Thanks Dave for your thoughts. My fully registered friend has had a look;) and checked the continuity of the wire from the switch to the element and that is ok. The switch itself although is not notchy or anything the points are all a bit black and the section on the cam that controls the element in question does look slightly burnt and has a slightly small notch out of it. Its position 9 and on closer inspection that part of the cam is a flat square that looks like it should be pressing on a point but does not because of the burnt out notch.
I think this is the one I need – is that right.
http://shop.ukwhitegoods.co.uk/050028-delonghi-homark-caple-oven-selector-switch

[electrofix]

funny isnt it

got identical fault on same cooker last night

looks like thats the correct sw as i am ordering the same one lol

Dave

[menderman]

Bet you didn’t break the two red indicator lights like I my fully registered friend id 😮 – when they removed the front pannel.
Now need a way to repair it.

[electrofix]

not taken top off yet

i know its the sw because element goes on and off if you waggle knob

got to hope all the burner screws extract as its a killer if too many snap

Dave

[menderman]

I tried wiggling the knob but it made no difference. My top was off 5 years ago for the same burnt out switch so the screws played nicely.
From now on I will adopt the correct method of turning the selector first then the stat to turn on and to turn off it will be stat off then selector. Apparently turning the selector with the stat (power on ) can cause arching and burning. Makes sense to me as that’s the element we mostly use and that,s the selection on the switch that fails

[menderman]

Update.
I brought the new switch from here this one and as the switch had been replaced before it was an exact match (the oem one was brown and slightly different)
Fitted and all working ok. So thank you Dave for your help there.

BUT everything was tested before the top was put back on and all elements were ok. With the top off took the opportunity to clean some of the surfaces as they were dark brown I was very careful not to get anything wet and used a foam cleaner a small section at a time.
After the top was but back a and a final test done there was a small “pop” and the whole oven went off and tripped its RCD. It could of been a pop noise or its just the noise ove everything going off in one go.
turned back on and currently testing one element at a time.
Just tested the top and bottom element position and both elements work ok, stat comes on and off maintaining temp and cooling fan comes on after about 20 mins and 185 degrees oven temp, fan also stays on for 15mins after turning off.

Will report back with grill element test.

[menderman]

Grill element is working ok, and stat comes on and off keeping it at the 150 I set it at. Also works ok with grill and fan setting, 3 mins after turning it all off the cooling fan came on, I have a separate thermometer in the oven to check against the stat temps and that read 175 degrees. The fan came on for 8 mins.
So it looks like the cooling fan is working ok too.

Next up the fan element.

[menderman]

The fan ring element is also working ok – tested up to 225 degrees and the cooling fan kicked it at around 190 degrees as read on the separate oven temp gauge I placed in the oven.

So what could of caused the trip ?
The only thing I can think of is that I have known a bulb blowing to trip an RCD but the bulb is working ok. But I have also seen these filament bulbs blow but then the filament catch and re attach itself. I will look at the bulb once the cavity has cooled down.

[electrofix]

elements can soak up moisture over time if not used

if the ingress is not too bad once you heat them up they blow the trip a few times as the water is expelled then they work ok

just see how it goes

Dave

[menderman]

electrofix wrote:elements can soak up moisture over time if not used

if the ingress is not too bad once you heat them up they blow the trip a few times as the water is expelled then they work ok

just see how it goes

Dave

WOW I did not know that. It only did it the once.
We actually never use the grill in the cavity I was testing the new switch on, the top element is a double bend with the inside run being the grill and the outside run the oven, as its big we always use the smaller grill on the other oven cavity instead so yes an unused element and it matches up with what you say.
I don’t quite understand though how moisture can stay in an unused element when it is in the same cavity being heated by other elements to over 200 degrees.

[electrofix]

the element is a steel tube thats insulated with a powder. this powder can draw moisture out of the air over time

see how it goes

Dave

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