Cooling fan issue

[WoodScrew]

Can anybody please assist with a cooling fan issue on the following:
Britannia SI-E10T-DL-C electric double oven
Art no. PDE100MP
Serial no. 05260543

The front control panel fascia was clearly getting hot as the temperature increased in the void containing the sensors, wiring etc. resulting in the activation of the Safety Thermostat. After approx. 10 minutes cooling down, power resumed to the programmer which enabled the timer to be reset to enable oven function. As a consequence, I replaced the Dual Phial Thermostat (A49206) which appears to be working, controlling the oven temperature as expected.
My concern however, has been drawn to the COOLING FAN which serves to keep the control panel and control knobs cool during oven use. After the oven has been in operation for approx. 45 minutes and being thermostatically controlled it should cut in, however there is no airflow venting from the slots sited in the front control panel. I’ve checked the fan blades rotate freely. Isolated it from the oven and applied power directly via the terminal contacts and can confirm it’s working okay. I’ve checked the temperature knob sensor using ohms reading and confirm it operates when exposed to external heat source.
Is it possible, following the initial Safety Thermostat activation another component has been adversely effected due to exposure to excessive heat. Are there any thoughts as to where I look from here?

[electrofix]

dont have any tech on these but there are various ways to operate the fan

i would trace both leads and see where they go

it could be

1 thermostat the cuts in when it gets hot
2 circuit board that turns on fan when anything switched on and keeps it running for a while to cool things down after use

its unlikely any other component has been damaged by heat because the overheat stat is set so it stops damage

Dave

[WoodScrew]

Thanks Dave for your prompt attention.
I’ve traced the wiring to the front panel knob sensor stats (2no. Linked) and rechecked for continuity. The thermostats are ‘open circuit’ and when exposed to heat respond by closing giving a resistance “0” ohms reading which suggests okay. The circuit board appears to be an integral part of the PROGRAMMER assembly. I am not sure how to check if this has failed other than to replace it. Can you offer any further thoughts or is it a question of “sucking it up” and purchasing a new one.

[electrofix]

If you link the wires across the n/o stat does the fan run

also how much heat did you add to get it to close ?

Dave

[WoodScrew]

Dave thanks again for coming back with your posting.

I can advise by linking the wires, in effect isolating the stats, the cooling fan runs.
The original test carried out on both front panel sensor stats to confirm working was undertaken by exposing them to heat by placing on a griddle for approx. 30 seconds in order to raise the temperature above 60 *C which is identified as the activation level. I’m unable to confirm the precise temperature, but naturally it would’ve had to have been in excess of this. Is it possible, the solution lie in replacing both stats, assuming the operating temperature has to be elevated well beyond the calibrated level before closing and powering up the cooling fan. Would this eliminate the circuit board being at fault?

[electrofix]

well it these stats are faulty it would stop fan running. the safety stat goes out stopping everything. if they activate the fan its hoped the safety stat would not trip allowing cooking to continue

Dave

[WoodScrew]

Dave I appreciate your follow up.
I’ll replace stats and with a bit of good luck, the problem will resolve itself.

[Author]

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