Oven cooling fan thermostat query.

[TWO]

Hello & hope somebody can help.
When the small oven or grill on a Smeg double oven is turned on, the cooling fans are not coming on, causing the control panel and knobs to become blisteringly hot.
Both the tangential and rotary cooling fans operate when the lower oven is used.
The cooling control thermostat (on the rear upper frame) was suspected, BUT if hot air is blown onto (it from a heat gun) both fans do run.
Therefore the problem seems not to be with the cooling fans or their control thermostats.
Any other suggestions would be very welcome.

[kwatt]

That top oven selector switch would be the first thing I’d look at.

K.

[TWO]

Thanks for the speedy response. What is the reasoning for suspecting the selector switch? Can you identify the part for a Smeg DO44SS-5 or a compatible substitute, please?

[kwatt]

Suspect because the bottom oven is working and it’s the same fan and stat in play so the switch is the only thing in that not common to both really or, anything else is pretty exotic.

It’ll be a DO4SS-5, no DO44SS exists.

The switch is:

https://shop.ukwhitegoods.co.uk/811730234-smeg-oven-selector-switch

K.

[TWO]

The lower oven does have its own stat linked to the fans.That’s why I thought it was the upper stat. Still don’t understand why the selector control would directly affect the fans as they have a live feed available for overrun even when the selector is off.

[kwatt]

Because something has to tell the cooling fan to energise and the only thing you move to do that on each oven is the switch.

K.

[TWO]

Thanks again. You work later than me.
I still don’t “get it”. I thought the fans had a constant live supply but were activated when the stat reacted to temperature rise and closed to make the circuit. So where does the selector control play a part in the circuit?

[kwatt]

Possibly but it’s the only thing I can think that changes.

Logically the fan is the same for both ovens. The fan initiation stat is the same. The overheat is the same. So if it was not working on one oven, it wouldn’t be working on either or, vice versa.

All that changes in use are the switch and oven thermostat, the oven thermostat for each oven having bog all to do with the cooling system in any way. Which only really leaves you the switch before you get into exotic weird stuff that is unlikely.

There is only one tangential cooling fan motor in that oven, blowout attached of it.

Blowing hot air into it doesn’t really prove a lot other than, the fan works as does the initiation stat.

K.

[TWO]

Agreed the oven stat is irrelevant and that is not what I referred to. There are two fan initiation stats for the single tangential and rotary cooling fans. Hot air gun was aimed at the upper stat, after moving it away from the attachment bracket, to confirm that the stat was functioning.

[kwatt]

I prefer testing to guessing, just saying no offence intended. 😉

Open it up, check stuff, it’s the only way.

K.

[kwatt]

Dug a bit and there are actually two fan initiation stats in it, looks to be one for each cavity and both are this one:

https://shop.ukwhitegoods.co.uk/818731204-cooling-fan-thermostat

So it’s possible the one for the upper oven is shot.

K.

[TWO]

kwatt wrote:I prefer testing to guessing, just saying no offence intended. 😉

Open it up, check stuff, it’s the only way.

K.

None taken;) and so do I,. there’s no guess work–its application of logic, but the b*****d was open, and so the stat is exposed and not subjected to oven heat but it does respond to heat gun test.
Thanks for the part ID. I will try swapping those two stats around, sometime.
Is there any compatible stat I could use instead, even if it means losing the connector block and 3 wires)

[kwatt]

Nope, that one is the only show in town for that oven.

K.

[TWO]

OK. This job will have to take its place in the queue, but thanks for your input.
Good to find this forum.

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