Oven Control Switch

[cajunbanker]

I have an antique Kenmore gas range, Model #143.6106800.  The oven control was replaced many years ago and it appears to be out again as it will not ignite the oven.  The pilot light is on but gas is not flowing to the oven burners.  The range burners work fine.  Attached is the current controller information and looking for assistance on where to purchase a replacement.

 

[Budget Appliance Repair]

My bet would be the oven t-stat isn't your problem - this old system if it has a standing pilot flame with this electrical oven t-stat you most likely also have mercury flame sensor, (it would be a little tube that sits in the pilot with a thin looking wire - it's actually a thin capillary tube which connects to the switch/bellows that closes with the heat from the pilot heating the mercury in the capillary tube expands and moves the bellows that is connected to the switch.

If the pilot flame is heating the sensor good then the mercury flame sensor is most likely bad.

Just for testing purpose you can remove the flame switch from where it's mounted near the oven gas safety valve and connect the two wires that attach to it together, (MAKE SURE IT'S UNPLUGGED and the two wires when connected together can't touch anything), then plug back in and turn on - if the flame switch is bad the main oven burner will light now because you have bypassed the flame sensor.

The model number you supplied comes up as a range hood, (?maybe a combo with the range) - Sears site had the model number but shows no parts available and not a good enough pictures to see if the hood is part of a range.  Model number doesn't come up anywhere else.

Need pictures of the oven gas safety valve and pilot assembly to know if it's the type of system I describe above, (pretty sure it is from your picture of the oven t-stat and saying it has a pilot that is lit).

Edited December 7, 2024 by Budget Appliance Repair

[cajunbanker]

Willie,

      Thank you for replying.  You are correct, this model does have a range hood.  I have attached a couple pictures to show what the set up looks like.  In lieu of testing, I would simply replace the flame sensor as this is the original since acquiring this range.  

      Your thoughts and suggestions on where to purchase to include replacing the pilot assembly if needed.  

[Budget Appliance Repair]

That is the style of system that I thought it was and was explaining.

Do you know what part is the flame sensor?  (it's in your last picture at the back left of the main oven burner - has the looping thin capillary tube running to it.

The pilot flame looks like it's burning OK - the sensor tip of the flame sensor that is in the pilot flame doesn't appear to be in good shape.

I wouldn't advice you to just go and replace the flame sensor - first of all, it can be a very expensive part if you can even find one. UNPLUG THE RANGE then it doesn't take but one or two screws to remove the main switch part of the switch from it's mounting bracket and remove both wires from it and slip the two connectors together and tape with electrical tape, plug range back in and do a quick test.

Search Ebay for "Flame Switch" or "Flame Sensor"
The main difference are the length of the capillary tube. (the ones that where originally made for these ranges came in 14" and 26" capillary tube and the sensor tip mounts different on different models).

As long as the capillary will reach from the pilot mounting point to where the main switch body mounts they will all work and looks like the sensor mount at the pilot is just the tip of the sensor squeezed between the end of the pilot to hold in place.   (some of the flame sensors come with a short piece of stainless wire to wire the flame sensor to the pilot).

Approximately $200 is the going price range on Ebay, (last one I found about a year ago I found by searching the internet and found one at a surplus outlet and got it for under $100).

Here's a few that look like they would have a good chance to make them work/mount OK.

Attached is a page from an old parts book with the original Harper-Wyman
part numbers that might be something to search with these part numbers to find one.

 

#2 the capillary tube maybe to short

1) https://www.ebay.com/itm/185696994870
2) https://www.ebay.com/itm/181753776909
3) https://www.ebay.com/itm/181923288626
4) https://www.ebay.com/itm/184398573443

 

[cajunbanker]

You have been most helpful.  I will take your advice and let you know what happens.  Thank you and will be in touch.  

[cajunbanker]

Willie,

      I unplugged the electrical, removed the two wires and taped them together, plugged the power back in but the stove did not light.  Thought maybe didn't have a good connection so tried again but with the same results.  

      Looks like I will need to purchase that flame switch anyway because when I put the tip back on the pilot mount, it broke off.  

      Any further suggestions especially on where to purchase the oven t-stat.  Again I appreciate your help.  This stove holds a lot of sentimental value for my wife because it was her parent's stove.  When I finished rebuilding it, my mother-in-law wanted it back.  

[Budget Appliance Repair]

There's still a possibility it's not the oven t-stat, (you did say it was replace quite a few years ago).

You need to check the gas safety valve to make sure it's not open, (use your meter on OHM setting and make sure you have continuity between the two wire connectors on the gas valve.

That might be an aftermarket RobertShaw oven t-stat that was used as a replacement - you're going to have a hard time finding any parts by model number.  Use the numbers on the back of the oven t-stat to Google search to see if you can find a replacement.

Did you remember to plug the power back into the range after bypassing the flame sensor and of course relight the pilot, (sorry to hear you broke the flame sensor as it might not have been bad - you really shouldn't have been even messing with the pilot end just for testing to see if it was your problem).

Also just thought of one other possibility - Does this unit by any chance have a clock with the cook START/STOP times, if so it might just be in a timed bake mode instead of manual bake and if you don't reset it to manual bake correctly no mater what you do you won't get the oven to work.

[cajunbanker]

Thanks again.  I did remember to plug the power back after bypassing the flame sensor and relit the pilot.  The reason I had to mess with the flam sensor is because after testing the second time, the sensor came off of the pilot and when replacing it was when it broke.  I am expecting a new one to arrive this week and will test the gas safety valve as suggested.  It is not easy to access the flame sensor as I need to remove the whole back panel which means removing the duct vent and pulling the stove away from the wall.  By the way, yes there is a clock and yes it set to manual bake.  Will be in touch with my next test.

[Budget Appliance Repair]

You shouldn't have to go thru all that to replace the flame sensor - you can see it in the picture in the oven burner area - there are only two screws that mount the body to the mounting plate all.  All access should be in the area that you have pictured from the front.

If you mean to get access the safety valve - then from your picture it looks like it might be not accessible so easily or at all from the front area like it would in a normal freestanding range.

[cajunbanker]

That's what happens when you DIY and not sure what you are doing.  The first time I did access from the back but then realized I could access from the front.  the front access is just as tight of a fit as the back, just with less trouble.  When came from the front is when the flame sensor came off and eventually broke.  

[cajunbanker]

That's what happens when you DIY and not sure what you are doing.  The first time I did access from the back but then realized I could access from the front.  the front access is just as tight of a fit as the back, just with less trouble.  When tried from the front is when the flame sensor came off and eventually broke.  

 

Received the new flame sensor.  Attached/connected it and made sure the tip was in the pilot flame.  Plugged back in and nothing happened.  I went back and did the test as before of connecting the two wires but will not come on; then tested the OHM and nothing showed on the meter (not sure if I am doing this part correctly).  Does this mean it might be the gas valve?

[Budget Appliance Repair]

Test the OHM's where?

Unit unplugged - at least one of the two wires that go to the gas safety valve disconnected and check OHM's across the two terminals of the gas safety valve.  The gas safety valve if bad will show either a somewhat low reading of the OHM's of the valve, (I don't know what the reading will be but probably under 200 OHM's range if good, OPEN/Infinity if bad).

If you have your meter is on the correct setting and touch the two meter probes together you should get a reading of close to ZERO OHM's - meter probes not touching you should get a reading of infinity/OPEN however your meter shows this.  Hopefully you understand the basic use of your meter.

To check the new flame sensor with pilot lit and at least one of the wires removed from the flame sensor and check OHM's across the two terminals of the flame sensor, (if the new flame sensor is working correctly - which it probably is you should get a reading close to 0 OHMS = closed circuit = flame sensor sensing that the pilot flame is lit).

If both the flame sensor and gas valve show the correct OK readings then you will need to do some live voltage test and find where you are loosing the voltage thru the oven t-stat system.

I'm not going to try to go into live voltage readings with you - I have no wiring diagram to even start to try and guide you.

You would need to know what the different terminals are on the oven t-stat to see if it might be bad again.

I have no idea if you have a selector switch for oven BAKE/BROIL/OFF/TIMED BAKE or if just the clock for manual and timed bake and BROIL/BAKE options all in the oven t-stat.

If just BAKE/BROIL on oven t-stat and no switch to select options then timed bake would be completely thru the clock controls and you would again need the wiring diagram to know what to check to see if it is correct.

Maybe a picture of the control console area with all controls and the clock to help to see if you have it set correctly.