Oven not quite getting hot enough after repair, and occasionally cutting out.

[aardvaarkk]

Hi, a while ago I repaired an elderly Whirlpool G2P 62F/01 with help from this forum (thanks Dave!) — the element blew and took the relay with it. Both replaced.
The oven has been working pretty well except that:
1) we’re pretty certain it’s not getting quite as hot as it used to (before the repair) and
2) recently, every so often the light and the element cuts out.

Do we have two problems or one connected problem?

For (1) the front panel controller /thinks/ the temperature is ok, switching the element as normal, so it’s as if the thermostat is over-reporting the temperature. I can’t find any calibration knobs for the thermostat. Why would replacing the element affect the thermostat?

For (2) the front panel controller carries on oblivious. The fan keeps whirring too. Slamming the door usually fixes it, so it looks like a loose connection, but I haven’t been able to locate it.

Thanks for any help or ideas!

[electrofix]

try getting an oven themometer and see what temps you have got

Dave

[aardvaarkk]

Hi Dave — temperature reads about 25 degrees C low (using a dangling digital meat thermometer, and searching for the hottest spot), so it never gets near the “max” of 250. Though we didn’t measure it before the repair, we know that food takes significantly longer to cook than it did.

[electrofix]

check the sensor

resistance is listed as

1000Ω + 3.75 x Temp

Dave

[aardvaarkk]

ok, will do next week — I’ve been banned from interfering with the oven before christmas 🙂
Have a happy christmas yourself!

[aardvaarkk]

I’ve measured the sensor at about 1055ohms @ about 16 degrees room temperature. That seems pretty close to spec? The sensor doesn’t appear to be bent or touching the metal, so I don’t know if this is the cause of the under-heating.

As for the heater element+light going off at random I’m not much further on. When they are off the controller doesn’t seem to care, and all the front panel is alive, just that the temperature falls (as you’d expect.) Slamming the door in the right way usually fixes it, though it can go off again a short time later.
The shared connection between light and element is the neutral wire which passes through what I believe is the thermal cut-out (see image below) on the way back to the power block on the mains supply side. I’m trying to work out if the thermal cut-out is sensitive to vibration, but it doesn’t seem to be when cold at least. Could it be the problem when hot? I’ve temporarily by-passed it and will (carefully!) determine if the problem has gone away over the next couple of baking sessions.
[IMG2=JSON]{“data-align”:”none”,”data-size”:”full”,”height”:”185″,”width”:”200″,”src”:”http://invisibules.org/wp-content/uploads/2022/01/IMG_20220102_1119417071.jpg”}[/IMG2](I found this part online for about £40, which seems expensive given that other makes have them for under a tenner, eg: https://www.ebay.co.uk/itm/142870009152 — would it be reasonable to use one of these instead?)

Happy new year!

[electrofix]

as for sensor it seems about ok
after that it could mean a board fault and that starts getting expensive as there are 2 boards

you need to try and find the intermittant error you never know the 2 faults may be connected in some way

Dave

[tubafan]

The fact that slamming the door ‘wakes it up’ suggests bad connection, bad solder joint, or sticking relay to me. I’d be examining the boards very closely for the first two and giving the relay a gentle tap for the last. Are you sure the relay you replaced is rated for the correct voltage as an over rated one (eg 12V relay replaced with 24V) could also cause intermittent operation.

[electrofix]

as for the temp limiter
you would need to know the operating temp to find an suitable replacement

the gen part no should be 481228228263

there are 3 or 4 versions of your oven but not checked them all to see if stat the same

would need the 12nc number to tie the right one down

Dave

[aardvaarkk]

Thanks Dave. I’ve temporarily by-passed the temp limiter and will (carefully!) determine if the problem has gone away over the next couple of baking sessions.

The fact that slamming the door ‘wakes it up’ suggests bad connection, bad solder joint, or sticking relay to me.

I don’t think it’s a relay: Slamming the door can also turn it off (and, why would it have gone off in the first place?) But I will check later, thanks for the tip. When I fixed the relay before I just moved an identical but unused relay from elsewhere on the board. The rating is the same. Also, that relay controls only the element, not the lamp.
Bad wiring/soldering is more likely. I started investigating the wires, but whatever it is has to be common to the element and the lamp (and, I think the grill, but I haven’t checked) and nothing else. Which is why I focussed on the thermal limiter. But you are right, there could be other common paths.
The thermal limiter says “Type 261/PB” which seems to indicate the basic shape and function — normally closed and with a reset button?
Then 16/3 250~ which I think is the current/voltage rating? And then T175K which I suspect is the temperature of cut-out in … Farenheit — about 80 celcius?
What is the 12nc number?
cheers

[electrofix]

the 12 nc number will be on the label with the model and serial number

its the commercial code of the oven. they can use the same model in catalogues and change the commercial code when parts change

Dave

[aardvaarkk]

[IMG2=JSON]{“data-align”:”none”,”data-size”:”full”,”height”:”83″,”width”:”800″,”src”:”http://invisibules.org/wp-content/uploads/2022/01/IMG_20220102_121105069-scaled.jpg”}[/IMG2]
Presumably one of those barcodes is the 12nc, and one is the serial?
Anyway, it doesn’t matter now, because even with the thermal cut-out bypassed the bad behaviour remains — so it’s not that. (You’ll be happy to know that the ginger biscuits turned out very well, even though I had to shake them several times to keep the oven on 🙂 When it’s cool I will open it up again and do some more searching.

[I had another thought about the low temperature. I’ve realised that when the oven runs some air is constantly expelled through the door — so I think this would explain the low temperature? (And, not to mention sending my electricity bill soaring… and why it’s so hard to keep steam inside for baking.) I could replace the seal.]

Thanks again.

[electrofix]

yes 8541 is commecial code

and info above correct. its says if sensor in range then must be control unit problem

there is a cold air fan that blows air out of the top of the door. this air becomes warm as unit heats up but does not mean the internal air is escaping

also there is a vent in the oven so steam will escape in every oven

Dave

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