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FIXED 790.79523600 Kenmore Pro Oven Won't Heat Up

bldn10

Premium Member
Joined
Jun 28, 2014
Messages
22
Location
Memphis
Model Number
790.79523600
Brand
Sears Kenmore
Age
More than 10 years
This is a 10-year old Kenmore Pro dual fuel freestanding range model no. 790.79523600. I don't use the oven much and frankly am not sure if it ever worked correctly.
in Bake mode it will not heat past around 250*;
in Broil mode, the top element gets red hot as it should,;
in Convection Bake mode, the fan comes on but the elements are as in Bake mode.

I have replaced the temp sensor and Oven Relay Control Board, I'm getting 240v to the elements, they get somewhat hot and appear to cycle normally - just don't get hot enough. All have continuity. I have the lower element out and it looks like new w/ 23 ohms.

A question I can't seem to get answered is whether an element either works or it doesn't. I.e. if it gets even a little hot does that mean it is OK? Similarly, if the elements are getting even a little hot does that mean that the High Limit Switch is OK? If the HLS, ORCB, elements, and temp sensor are all OK, what's next - Oven Control Board behind the front panel?

Any and all help appreciated. I'd like to be able to have a frozen pizza every now and then.

Bill/Memphis

Added complete model number
 
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Dan O.

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Kenmore range model no. 790.79523
That model number is incomplete. What's the rest of it?

You can find tips for locating the model and serial number identification tag on your appliances at the following link. That's the only place the complete information will usually be found.

LINK > Model Number Tag Location Guide


bldn10 said:
A question I can't seem to get answered is whether an element either works or it doesn't.
That's correct.

LINK > How do I test an electric stove element?

bldn10 said:
if it gets even a little hot does that mean it is OK?
That's correct although it could also have a partial short to ground.

bldn10 said:
I'm getting 240v to the elements, they get somewhat hot and appear to cycle normally - just don't get hot enough.
That's impossible. If it's getting the full 240v they should get red hot.

Something not right with how you're measuring it.

JMO

Dan O.
 

bldn10

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Messages
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Location
Memphis
I have the lower element out on the floor - it's not shorting. So I'm going to say that the elements are not the problem.

"If it's getting the full 240v they should get red hot."

Dan, as I'm sure you know, even on Bake the lower (hidden) element and the broil element both operate, but not at the same time - they cycle. It seems to me that neither stays on long enough to get really hot, certainly never red. I actually put my meter on the contacts while on Bake and saw first the lower come on for maybe 20 sec., then the upper, then a pause, then start all over. It's obvious when they switch because you can hear the relays. Does the OCB control the element duty cycles?
 

Dan O.

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bldn10 said:
I'm sure you know, even on Bake the lower (hidden) element and the broil element both operate, but not at the same time - they cycle.
I don't know anything about the range without a proper model number besides the 790... indicates it was made by Frigidaire/Electrolux.


On models that cycle between bake element and broil, the electronic control would usually be responsible for the timing of the elements heating, yes.


.
 

bldn10

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Memphis
790.79523600

I found another thread and what sounded like a similar problem was fixed w/ this control behind the oven temp knob. 318601500
 

Dan O.

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I actually put my meter on the contacts while on Bake and saw first the lower come on for maybe 20 sec., then the upper, then a pause, then start all over.
Your model's tech sheet says:
Tech Sheet said:
Bake element is on 25 seconds per minute. Broil element is on 15 seconds per minute. Convection element is on 20 seconds per minute. The convection fan is on all the time but it stops once the set temperature has been reached.

The EOC will cycle through the bake element and broil element to maintain the set temperature.


Part # 318601500 is a potentiometer. While it is also used on your model, I'm afraid i have no idea how it could be responsible for your stated symptoms.

The control system used on your model consists of several different electronic control boards. The display board # 316460300, the "Analog Control Board" # 316460202, and a separate relay board # 316443915 that does the actual switching of the power. If the control's logic is faulty, I might suspect the analog control board. If power was dropping out unexpectedly, the relay board might be suspect.

There is a note in the 'tech sheet' about recalibrating after potentiometer or analog control board replacement. Maybe you could try just that first?

LINK > 790.79523600 Tech Sheet # 318204800 (PDF)

I'm afraid i do not know how to narrow down the possible causes.

Dan O.
 

bldn10

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Thanks for the Service Manual - learning from it. So the cycling I saw seems to be normal. As the bake element is on for 20 secs., off for 40 secs., and back on and so forth, iIs that 20 secs. out of each min. long enough for it to get red? I just bought a cheap infrared thermometer that seems to be pretty accurate and after several cycles the actual lower element tube got to 300*. On Broil the upper element is turning red w/i 20 secs.
The mode w/ the longest lower element duty cycle is Conv. Roast, in which that element is supposed to be on for 30 secs. per min. I thought that 30 secs. might be long enough for the element to start turning red. However, my oven is cycling every 20 secs. in Conv. Roast. Something awry there.
I just checked the voltage again and have 237 on the lower element when it is in cycle.
A friend told me that it was possible that the conductor w/i the element could be broken somewhere inside and is making a connection to the ground/neutral to complete the flow of electricity, but not enough to make it heat completely. I suspect that that is unlikely but is it even possible?
Should I just bite the [another] bullet and try a new element?
 

Dan O.

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bldn10 said:
Is that 20 secs. out of each min. long enough for it to get red?
No, it would likely take several minutes of constant 240v to glow red hot.

A friend told me that it was possible that the conductor w/i the element could be broken somewhere inside and is making a connection to the ground/neutral to complete the flow of electricity, but not enough to make it heat completely. I suspect that that is
While it may be possible, i think it very unlikely.

bldn10 said:
Should I just bite the [another] bullet and try a new element?
I very much doubt the element is responsible but I'm afraid I have no idea of the cause of your symptom. Sorry.


Did you try the recalibration with the potentiometer described in the tech sheet?

Dan O.
 

Dan O.

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Did you check the convection element? Acording to the tech sheet, it is suppose to be on during preheat as well.

Dan O.
 

bldn10

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Conv. element has 240+ to it. I did the calibration and it was only off a few degrees. I think that is really for fine tuning temp.

Do you have any idea how hot the actual lower element tube should get? After several cycles it is getting 330* or so. Even w/ the broil element, would that ever heat the oven to, say, 450*? Keep in mind that the lower element is out of the unit.
 

Dan O.

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bldn10 said:
Do you have any idea how hot the actual lower element tube should get?
I do not, sorry. I don't have acces to a service manual for that product.

bldn10 said:
Even w/ the broil element, would that ever heat the oven to, say, 450*?
I would have through a hidden bake element would have to get hotter than a conventional element to heat the floor panel as well. It can't get that hot only being powered for seconds every minute.

I'm afraid I don't have any other ideas.

Dan O.
 
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bldn10

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I did another test of the cycling and in Bake the bottom element was on for 25 secs. per min. as it should. Since it seems to be cycling properly would that mean that the problem is NOT the Range Oven Control Board aka Analog Board? If so, I suppose that I'll just have to try a new element, although this one looks like new.
 

Dan O.

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Since it seems to be cycling properly would that mean that the problem is NOT the Range Oven Control Board
How long did you check it for? It might be possible for the control to operate properly at the start of a cycle but malfunction after operating for a while.

bldn10 said:
Conv. element has 240+ to it.
When you checked the operation of the convection element did you test it for continuity or feel it actually heating? If the element was defective it could be getting power but still not heat.


bldn10 said:
I suppose that I'll just have to try a new element, although this one looks like new.
As I said, an element either works or it doesn't. I'm sure it's a waste of time but if you want to see for yourself, it shouldn't hurt anything to try replacing it.

LINK > FAQ: Electric Range Element Operation

LINK > Kenmore 790.79523600 Bake Element



Dan O.
 
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bldn10

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Well, heck, I tested through about 10 full cycles, which would be 10mins. But I've let it run for like 25 mins. and it only gets around 250*. How long do I need to do the cycle test?
All 3 elements heat up.
If trying a new element is probably a waste of time do you think trying the Analog Control Board would be less so? It does not look like we can determine what is really the problem here until the bad component is swapped out. All we can do is try the most probable in order. FWIW the element is cheaper than the ACB.
 

Dan O.

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bldn10 said:
heck, I tested through about 10 full cycles, which would be 10mins. But I've let it run for like 25 mins. and it only gets around 250*. How long do I need to do the cycle test?
That should be plenty. If the problem occurred during preheat, the cause should have been seen by then.

bldn10 said:
If trying a new element is probably a waste of time do you think trying the Analog Control Board would be less so?
I'd really hate to say it's the board since it appears to be cycling the elements as described in the tech sheet.

I really can't understand how the oven can heat properly with the elements only being on for seconds each minute. But I definitely think the element itself can't be the problem if it heats when powered.

bldn10 said:
FWIW the element is cheaper than the ACB.
True but it should also be the easiest to rule out.


Sorry but I don't have any other suggestions. :/

Dan O.
 

bldn10

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Got a new lower element and plugged it in laying on my tile floor. It gets no hotter than the original one. Neither the lower or conv. elements get much over 300 in Bake, the broil element does get over 400 but, like you, I don't understand how the oven would get to 400 in any reasonable time, if ever.
I guess I'm on the the analog board.
 

bldn10

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Rick, are you saying that is the part because I said that was my next step or do you really think that's the problem?
Can you shed light on how the oven can ever get to say 425* when no element is on longer than 25 sec./min.?
 

rickgburton

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The Electronic oven control relay board (the one you replaced) serves to energize the oven heating elements, convection and door lock motors, cooling fan and oven lamp. The display board has the connection from the analog control board for the display and the LED's and keyboard inputs. The analog board controls the function selector, temperature selector, Potentiometer inputs and temperature sensor inputs.
Snapshot_1.jpg

Can you shed light on how the oven can ever get to say 425* when no element is on longer than 25 sec./min.?
Instead of one element on for 60 seconds per minute, you have three elements on for 60 seconds per minute just not at the same time. Dan O. is correct, The first rise is pre-heat. The Bake element is on 25 seconds per minute. Broil element is on 15 seconds per minute. Convection element is on 20 seconds per minute. (25 +15 +20 =60). The convection fan is on all the time but it stops once the set temperature has been reached. After that the EOC will cycle through the bake element and broil element to maintain the set temperature. It's all about saving energy. Now, a calibration procedure is required in the control to calibrate the analog inputs. A calibration procedure needs to be performed whenever the analog board is replaced, whenever a potentiometer is replaced or a temperature gauge is replaced. The calibration procedure in on the tech sheet.
 

bldn10

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I've done a new test but am limited being by myself. The optimum test of the cycling would be to have 3 multimeters plugged into the leads of all 3 elements. I could only do one at a time.

I first hooked up to the bake element and timed when it was getting its 240v. I can hear the switching so was able to also time the other 2. It worked correctly for 6 cycles, then a beep, and no cycling for over a min. I opened the door and it apparently reset because I got 1 good cycle, then another beep, then the bake was on 8 to 13 secs. for the next few cycles. BTW there was still 12v or so even when the bake was off-cycle.

Next up was the broil element. It worked OK for 6 cycles, then bake 18 secs., broil 6, conv. 8. Then a beep, then it stopped cycling and opened the door to reset again. Got 12-12-12 then several switching sounds, 5 beeps, then no activity for over 2 mins. 19-22 v off-cycle.

The conv. test was pretty similar - 4 good cycles, a beep, then no more switching, although one of the other elements could have been on. 18 v off-cycle.

If the analog board determines when each element should be on then perhaps it is the culprit.
 
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