Cannon cooker problem, please help is it the thermostat?

[happyhero]

Hi we have a Cannon C60etc free standing electric cooker and the oven is behaving a little bit erratically, ie you set it to 200 and it will beep and say its hot enough at 160 and variations on that theme. The way I check what its at when it beeps and says its reached temperature, ie you can turn the knob back and forth to see where it cuts in and out although with the playing about it is awkward.

The other way that we really know its not getting up to temperature is that the food is not cooking any where near the normal way so that some stuff just does not get hot enough or browned etc. Even on the highest setting its getting hot but no where near what it should get to.

I have had the control fail before several years ago and changed it, so when this problem occured this this time I changed it again as the fault seemed similar to me at first but now that I have changed it nothing has improved.

I'm thinking the only thing left that matters (obviously the elements are working as it gets hot, and I doubt a failing one would give such erratic results for so long without blowing....not sure if thats even possible anyway) is the thermostat.

I dont want to keep thowing money at this old cooker (about 8 years old or more I think) if we end up thinking its better to replace it but I think its obvious it must now be the thermostat, can somebody give me there opinion of this fault please?

Have I fogotton anything, or is this the next and only logical step left?

Any advice appreciated.

 

[Mark_FixCookers]

Am assuming this is a fan assisted electric

So you have

• Fan element (If it comes on at all which you have stated it does then the element will be fine).
• Stir fan (The one in the oven) Make sure it is turning nice and fast, this dissipates heat away from the thermostat phial (Sensor part of the thermostat in the oven) which generally sit right above the fan element behind or just above the fan cover. If the fan is noisy or labouring it may not always be turning fast enough to dissipate the heat away from the element quickly enough which will cause the thermostat to trigger too early cycling the power on and off before the oven. If the stir fan is at fault however this tends to cause uneven cooking as most of the heat is concentrated at the back.
• Door seal. They can collapse after a while, basically the fats, oils released during cooking settle on the rubber door seal and during cooling harden the rubber and because the seal cools down with the door closed, they stop pushing against the door reducing the seal effect. The typical fault this causes however is more uneven uneven cooking on the left or right side, sometimes at the front depending how bad and where the seal is not fully sealing.

Rule those out and you are left with a thermostat.

If you have a multimeter with a thermostat (Thermocouple) attachment or have one of those cookery oven thermostats (Which will only give you an indication), you can measure the temperature in the oven.
Probe has to be smack bang in the centre of the oven.
Set it to 200, leave it to to cycle on and off a few times, say an additional 10 minutes after the neon first goes out.
If your probe is sensitive enough, you take a note of the temperature the oven neon indicator comes on at and the temperature the neon goes off at. The half way point between those two temperatures is the operating temperature of the oven. If this temperature is 185 to 215 degrees Centigrade then the thermostat has passed. Allowed tolerance is ( +/- 15 degrees C)

Hope that helps

 

[happyhero]

Thanks Mark_FixCookers for all the advice. The fan was behaving oddly but then I don't know what it does normally. It does turn but quite slowly, I'm guessing here but lets say between 1 and 2 revolutions a second. I messed around with the oven settings and one time it went really fast like you would expect. Since that one time I can't duplicate that and it turns slowly. I turned it by hand and I feel a little resistantance possibly thats how it is, ie it wont spin freely like a bicycle wheel.

I'm wondering now if there is a reason for the slow spinning and the faults we are experiencing, to explain further when I decided to check the fan was free moving I had to take a cover off in front of the blades in the oven and hadn't realised that as well as the main element that was getting hot there was a round hidden element around the fan. Testing this with a multimeter shows it to be open circuit which could explain the oven struggling to reach full heat and taking ages getting there plus could it be the cuase of the slow spinning fan maybe being part of how it reacts to the loss of this element and its heat?

Anyway I ordered a new element and will fit and see what happens next and update on here. In the mean time I gave everything a good well over due clean. I cannot see if I should lubricate the fan though, is that something you do with oven fans and if so what do you use, WD40 would be all gone after a couple of times cooking wouldn't it?

 

[jj4091]

You need to remove the fan to degrease the bearings thoroughly & as you say wd40 is as good as anything.

 

[Mark_FixCookers]

No. Wd40 is a bodge. It won't last, the wd40 will evaporate away any other lubricant you try will only solve the issue temporarily

Fan elements do burn out but based on the information you have given, in your case the element will have burnt out prematurely due to the poor performance from the stir fan which dissipates heat away from the element so the element doesn't get to hot.
I would strongly advise you replace then stir fan motor when you replace the element. If you don't your element may last a few months or even a year, but it will burn out prematurely again.

Stir fan bearings tend to be the phosphor bronze type or a cheaper version of it. They are not ball bearing types.

 

[happyhero]

should the fan spin like a bicycle wheel.....one push and it goes for a little while?

 

[Mark_FixCookers]

It should spin a bit freely not as much as a bicycle wheel which uses ball bearings. But you have stated previously approximarely 2rpm on the odd occasion. It should spin pretty fast as in you cannot count thr rpms at all every time all of the time.

 

[happyhero]

Update, sorry it took me so long to come back on here but had to get my wife to give it a real test to be sure of everything. I ordered the new circular 1600W element and while that was on its way decided to completely remove the fan and see what I could find. I cleaned it up and lubricated it and in the end I did get it spinning like a bicycle wheel, ie one push and it spun for a while, which was a big improvement on before so I am sure that will improve things although I will keep an eye on it for a month or 2 as I want to see if it starts slowing again. I dont want it to slow and cause the element to blow again. It was tempting to replace it but I got it going so well I thought I'd wait and see, hopefully I made the right decision.

The only annoyance to taking the fan out was that it had a heat resistant sheet between it and the oven casing and this had cracked into 3 and so was a nightmare to refit, I would have put new if I had something similar but I couldnt find anything similar to cut to size, and I couldnt find it as a part to order so I assume it comes with the fan. Anyway I got it all back and it seems to be working great again thankfully. We were starting to consider replacing the cooker when this fault happened as its old, with the same one but I was shocked to find the same type is about £600 so I was really pleased I persevered and got it working for about £30.

Anyway thank you guys for all the help and guidance.

 

[Mark_FixCookers]

Don't worry about the white sheet behind the fan, these always disentigrate when you remove the fan. I have refitted new fans without these sheets and have never been recalled to them for any issues.
You will need a new fan at some point though. When your element starts going within 12 months then you will defintely need a new fan

 

[gasbanni]

The other thing is to ensure the oven door seal is in good condition and the doors seals against the oven cavity, you can check this with a strip of newspaper. Trap the paper when you close the door on it and check for resistance when you pull the strip of newspaper, if there no resistance and the paper pulls out easily the oven will, be losing heat.