Forum > Range, Oven & Cooktop Repair

Jennair Wall Oven broken Thermostat

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imzjustplayin:
I have a Jenn-Air W181 self cleaning wall oven that needs a new internal temperature probe/thermostat. This thermostat is used for determining how hot the internal temperature of the over is, it is not used for checking the temperature of meat or as a thermal cutoff switch. I contacted a parts supplier for whirlpool but they said that they don't manufacture the part I need anymore.

This is a digital oven albiet old and it works fine aside from this pesky old thermostat is giving invalid readings to the oven, making the oven think it's 900F when it's really 60F and 70F when it's really 400F. I'm pretty sure it's not a digital thermostat but probably some sort of thermo coupler that could easily be replaced by someone with electronics experience. Since this is a tech forum, I wanted to ask how I should approach such an issue where I need a replacement part/repair said part but they don't make it any more. So understanding the fundamentals of a temperature probe would appear to be a good idea.

Does anybody know much about temperature probes like how they work and how I should approach this issue? This oven isn't used that often and I really would like to NOT replace an entire oven because of a pesky thermostat as it has been trouble free since the day we bought it aside from this issue that is cropped up since last year.

Model W181

Repair-man:
I know a little about them...

That part you need is called the temp/clean thermostat, mounted thru the back wall. It was discontinued over 5 years ago, so start shopping for a new oven. No amount of tweaking wil resolve this issue. What is that , about 20 years old or more now?

imzjustplayin:
What do you know about this part? I'm not even sure if my part was actually broken when I took it out but now I'm sure it's broken because this little tiny wire that is used kinda like a Trottle Position Sensor on a car broke off. I'm trying to fix that. I think the reason why the thermostat broke or wasn't functioning properly (again I can't prove it wasn't working) is due to it being covered in soot. I think some other thermostat (which too is covered in soot) is the cause of the oven acting funny.  In low temperatures, the oven would say it's like 985F and cut off, once I heated the oven up with a blow dryer (I heated up the part listed in the OP and the one you have a pic of) with a blow dryer and the oven turned on, said it was 70F. Even at like 400F, the oven said it was like maybe 80F so I possibly had issues with two thermostats. I dunno, but again what do you know about this part? How can you tell if it's actually broken and why have you come to the conclusion that you can't tweak this part?

Repair-man:

--- Quote ---Does anybody know much about temperature probes like how they work and how I should approach this issue?
--- End quote ---


You don't go to the hospital and ask the surgeon how he knows his stuff...he just does, and he's not oblilgated to explain himself.

Your oven has at least one problem that I can identify, and if there was a cheap, easy way for you to get out of buying a new oven, I would be happy to tell you. It is in our best interest to sell you parts anyway, so if we tell you there's no way around a problem you can usually take that to the bank.


To address one of your questions, the part which is now broken and obsolete  is a combination oven sensor and high-limit thermostat for the self-clean cycle. Not only does it monitor the oven temperatures by means of an internal thermister (now broken), but contains contacts that are set to open at 975 degrees F during the self clean program. Later models did away with this type of control since it was too difficult to replace in the field versus a standard oven sensor. GE made a similar oven in the 80's that proved to be cumbersome also.

The part number last recorded for this is 702812...maybe you can  find one on Ebay.

imzjustplayin:

--- Quote from: Repair-man on January 24, 2009, 05:26:28 AM ---
--- Quote ---Does anybody know much about temperature probes like how they work and how I should approach this issue?
--- End quote ---


You don't go to the hospital and ask the surgeon how he knows his stuff...he just does, and he's not oblilgated to explain himself.

Your oven has at least one problem that I can identify, and if there was a cheap, easy way for you to get out of buying a new oven, I would be happy to tell you. It is in our best interest to sell you parts anyway, so if we tell you there's no way around a problem you can usually take that to the bank.


To address one of your questions, the part which is now broken and obsolete  is a combination oven sensor and high-limit thermostat for the self-clean cycle. Not only does it monitor the oven temperatures by means of an internal thermister (now broken), but contains contacts that are set to open at 975 degrees F during the self clean program. Later models did away with this type of control since it was too difficult to replace in the field versus a standard oven sensor. GE made a similar oven in the 80's that proved to be cumbersome also.

The part number last recorded for this is 702812...maybe you can  find one on Ebay.


--- End quote ---

You're saying that thermostat has an internal thermistor as well as a mechanical thermostat? The only thing I saw was what I'd describe as a mechanical thermostat where you have some porcelain, a metal rod at the end inside of a metal tube that pushes on a mechanical switch. That mechanical switch on top has an electrode that rubs against a conductive surface that sort of looks like a rudimentary circuit board where you have two wires coming out of opposite ends and you have a circuit path on this board, the electrode rubs against this surface and acts like what I'd believe would be a throttle position sensor in a car.

Then supposedly when that mechanical switch gets far enough, I think shorts out a 600F limit circuit and then shorts a circuit for the 985F circuit which explains why there are 7 electrical contacts on the outside of this thermostat. 2 connects for 985F "circuit" 2 connects for 600F connect and 3 for the wierd thermostat thing I described where you have two wires connected to a pseduo circuit board and a third wire connected to an electrode that rubs in the middle of this circuit board, up and down and supposedly reading the potential between one of those two wires connected to the pseduo circuit board gives a temperature reading??

Are you telling me what I described above is a thermistor? I'm pretty sure THAT is NOT a thermistor. There are three other thermostats in the oven which I KNOW ARE thermistors so I'm wondering if you're thinking of another oven or I just have an older/newer version of an oven than you're anticipating.

Can you explain to me why there are 4 thermostats for the oven? One has a 600F limit, one has that 985F limit, another has a 210F limit and the last one has a 175F limit (the last one I think is just for telling the internal fan for the electronics to turn on or not. Oh and no, those various thermostats do not all refer to that 702812 thermostat but actually refers to 4 separate devices.

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