GE Wall Oven - Fan turns off pre-maturely

Oven/Range/Cooktop Repair
1

I have a GE wall oven that prematurely shuts off the fan (for both ovens) after I have turned off the oven.

The model number is JTP35SM1SS.

That is, I can cook something in the upper oven at 350 or 400 degrees and the oven seems to work fine and the fan runs normally, then when I turn off the oven the fan keeps running for a period of time (maybe 5 or 10 minutes) and then it shuts off. After the fan shuts off the control panel above the upper oven gets very hot to touch over the next several minutes (after perhaps 15 minutes) as the heat escapes from the oven.

My understanding is that the fan should keep running as long as the temperature s above some level in order to keep the internal components cool. In fact, when running the oven, the control panel is either cool or warm to the touch.

The lower oven exhibits a similar behavior The fan runs while the oven is on, and then when I turn it off, the fan immediately turns off. The panel above the lower oven (in between the ovens) then gets hot as the heat escapes upward.

I assume the problem is the thermal switches in the oven that seem to control the fan operation. At least that is what I deduced from the diagrams and text in a service pamphlet that was taped to the inside of the oven. I have an extra control panel and the oven exhibits the same behavior with both panels.

I tested the thermal switches for continuity based on a video I found, and they do have continuity at room temperature. When the upper control panel gets hot (after running the oven), the switches for the upper oven read 1.2 to 1.5 ohms and thus also have continuity. If I remember correctly, I received the same reading at room temperature but I did not write it down.

Is it that the thermal switches that are bad? If so, could there be another problem that has resulted in the switches going bad?

The control panel is not showing any codes when I check it per the service pamphlet that was inside the top of the oven.

Another thing that has confused me is that one of the thermal switches in the top of the oven is not where the parts diagrams nor the service pamphlet indicate it should be. It is installed behind the upper fan (in a separate compartment (separated from the front of the control panel area by a piece of sheet metal) instead of in front of the fan as shown in the diagram and described in the pamphlet. Would this make a difference?

The part numbers for the thermal switches are:WB24T10060 and WB24T10118 (for the upper oven) and WB24T10127 (for the lower oven).

Thanks!

2

The thermal switches you mentioned in your post are for the door latches when you use the self clean. They are not connected to the cooling fans.

The cooling fans are powered up by the control board when you start any of the ovens in any cooking mode and should turn off after the control board turned off and the ovens cooled down to 150°F.

Unfortunately no thermostats for the cooling fans are shown anywhere at the diagrams. The only way to find them is to trace the wires from the cooling fans. In order to do it you have to remove the oven from the cabinet.

Here are the breakdown diagrams and Replacement parts for General Electric JTP35SM1SS ELECTRIC OVEN | AppliancePartsPros.com

Gene.

3

Gene,
Thanks for the reply. Perhaps I am confused…

Looking at the control compartment at the top of the oven (and the fan located there), I see three wires coming off of the fan. One goes directly to the control panel board and the other two go to the door lock mechanism. The other wires from the door lock mechanism go back to the control panel.

The lower oven, which has the same fan shut-off problem, does not have a door switch or lock.

According to the service information pamphlet that was found inside the control compartment, the cooling fans are controlled via thermal switches found in the control compartment. However, the information states that they are in front of the fan on the floor of the compartment. Instead, what I have is one switch in front of the fan and one behind the fan (behind the fan housing). See page 3 of the PDF at the following link.

Here’s a link to the pamphlet in PDF form: http://db.tt/PRPp8ygo

Looking at the diagram on the front of the pamphlet (which is duplicated on page 5 of that file), the switches I tested are connected via orange and blue wires (for the upper oven) and red/white wires for the lower oven.

For the upper oven, the other switch according to the diagram that is labelled ‘high limit switch’ is only operational when the bake or broil element is on; I believe this switch is located on the back of the oven.

Does it make sense that if the switches remained closed (even at a high temperature) that the fan would shut off before the oven has cooled off? My testing indicates that the switches are remaining closed (hence I can read a resistance across them at both room temperature and a high temperature after the oven has been shut off and the control panel has gotten hot from heat escaping up and out of the oven).

If it was not for the odd installation of the thermal switch (connected via blue wiring) behind the fan housing, I probably would have already just ordered new switches and given them a try. Perhaps I am a little too concerned about the one switch not being located in front of the fan as indicated in the PDF I linked to and (according to my reading of) the parts diagram you linked to.

Any insight would be helpful. Up to this point the contact I have spoken to at GE, who sent me the retrofit control panel kit, has told me they are not a service technician and cannot tell me left from right (fwiw, I did not expect them to be able to tell me much). Unfortunately the oven is out of warranty and they wanted to charge me to have someone come out and look at it.

4

1 This is correct per the wiring diagram. The upper oven fan speed depends on the lock position and is regulated by the switch in the lock assembly.

2 This is correct too and I did not find from the tech sheet how this fan speed regulates besides it has a tangential wheel.

3 Where in the pamphlet did you find it? It says on page 3: “The electronic control will turn the fan on at the beginning of any mode of operation. The fan will be turned off once the oven has cooled below 150°F”

It does not say anywhere that it has to be turned off by any thermal switch. The thermal switches in the control compartment are wired in series with the door lock switches and operate and control the door lock only.

The thermal switch for the lower oven is wired in series with the oven thermostat and controls power to the heating elements through the thermostat.

4 The high limit switches (they are present in both ovens) also called “thermal cutout switches” are a safety devices mounted to the rear of the ovens. Their purpose is to interrupt the power to the heating elements in case of overheating.

I believe the upper oven cooling fan shut off temperature controls by the oven control board through the oven temperature sensor. So, the correction for this problem, I believe, is replacing of the control board.

I did not find how the lower oven cooling fan shut off temperature controls. The pamphlet says nothing about it.

Gene.