JMC1116 Jenn-Air Microwave shuts down rather randomly, happens when a lot of steam in oven

[phillman5]

Model Number

JMC1116

Brand

Jenn-Air

Age

1-5 years

I think title says it all. When cooking various plates, especially if a prolonged cooking time, greater than couple minutes (but not necessarily on high power) the unit will completely shut down. This has also happened using a preset menu. The display will go dark, like there is no power. Opening the door and usually there is a lot of steam in the oven. Unit will come back after sitting for 1/2 - 1 hour (or more), display will come back.

I tried unplugging unit but that does not seem to decrease the time unit must sit to recover. Is there a sensor that has gone over active, or the board that the sensor plugs into decidedly over ambitious in completely shutting the unit off. This is a real pain when my wife has a few friends over for game night, and all the ladies have a dish that needs heating, after the unit turns off, no one else can heat their dish.

It wouldn't be so bad if the unit just stopped cooking and you could just blow out the oven to remove the steam, but the display going out says some board is shutting the whole unit off. When the unit stays plugged in, when it comes back to life the clock needs to be reset.

 

[Jake]

Hi,

You posted the Age as Less than 1 year old, is that correct? If so you have a full 1 year warranty on it from Jenn-Air.

1-800-JENNAIR (1-800-536-6247)

Jake

 

[phillman5]

Sorry about the age specification, Its beyond the 1 year warranty. I wanted to note that it was nowhere near 5 years old. I seemly can't find receipt (odd as we have a folder for major appliance receipts). I just talked to store where I bought it, and that was January 2018, so its out of warranty.

So can you help me diagnose this? Is there a board I can replace?

 

[Jake]

I just talked to store where I bought it, and that was January 2018, so its out of warranty.

Got it!

Yes, it sounds like the control board is bad.

But the control board is not listed on the parts diagram, which is very odd.

Unplug the microwave and remove the control board and see if there is a part number on it.

If so, post it here.

Jake

 

[phillman5]

Sorry for the delay.

There are two boards. The first 2.5 x 6 inches is right behind the keypad/display. It looks like the display is mounted directly to this board and a ribbon cable to the keypad.

It is silk screened and marked Midea VER:M1.31 , below that, 2016-12-19, which is probably the date. Off to the right: MD1001LB

Please see uploaded close up image of the top of this controller board, and an image of the overall board. I can probably get a better image if I remove all connectors and/or remove the board.

On the bottom, E173873. There is a sloppy ink stamp 11711157 which is probably the serial number.

There is a second board, ~ 1.5 x 2.5 inches, where both the incoming ~AC lines come into, and its output feeds the other components (load to looks like thermal switches and door switch in series, neutral to above board, I haven't done a complete wire trace). It just has a fuse, couple capacitors and a small torrid transformer. It seems to be a filter (either for spikes on the line, or to reduce noise to other items on the AC circuit.)

 

[Jake]

Nope, those are not the part numbers I need.

You'll likely need to take the microwave to a Jenn-Air service center where they can fix it for you. Contact Jenn-Air and ask them where to take it to for repair.

Jake

 

[phillman5]

You'll likely need to take the microwave to a Jenn-Air service center where they can fix it for you. Contact Jenn-Air and ask them where to take it to for repair.
Jake

Jake,
Sorry to bother you, but hopefully you can answer two questions.
After opening the microwave for the photos shown earlier, as mentioned there are, I believe two temperature sensors on the AC line, so if they opened, the microwave would shutdown as described. Those sensors are above the magnetron and on the outside edge/corner of the oven cavity.

For this unit, JMC1116, Jean-Air, says it can be "built-in" https://v1.jennair.com/appliances/details/JMC1116AS

I have uploaded an image of the unit in the cabinet, Image name "showing clearance.jpg". Jean-Air seemingly shows it can be in the middle of a cabinet (cupboards above and below the unit) recommends the opening being 17 high x 23 wide, I had 15" high x 24" wide, this leaves 2" of clearance above the unit 1.25" on each side, BUT there is nothing below the unit. I have also uploaded an image showing the trim piece I made: 'Trim.jpg', NOTE I put in vents into the trim (whereas Jean-Air shows no vents in their trim piece). To aid air flow, under the back of the unit I added two 1.5" diameter fans, see image 'fans.jpg'. The back panel of this unit has an exhaust fan, I put my fans just below this fan.

So my question is, do you think there is just not enough cooling (or allowance for exhaust air to leave cabinet) and therefore one the above thermal switches is opening? (Therefore taking it to a Jean-Air repair center won't help)

Anything I can do to allow more airflow: add another fan or two, or make the slots in the trim piece bigger?

Currently we are trying the unit without my trim piece installed.

 

[Jake]

The first photo is exactly how mine in my kitchen is, plenty of room on the top and sides, and I've never had a problem with mine in 5 years.

The 2nd photo looks like its not getting enough room to breathe.

I need to ask Rick about those other questions, he's much better at the inner workings of microwaves than I am.

Jake

 

[rickgburton]

Can you post a copy of your wiring diagram and or tech sheet?

 

[phillman5]

Can you post a copy of your wiring diagram and or tech sheet?

I did not find such inside the unit, nor did anything come with the users manual. There is a pdf on cabinet mounting instructions using Jenn-air's 'kit'. The specification tab on the website only gives dimensions. Even at appliancePartsPro they don't have an exploded parts or wiring diagram. The only parts they have for these units is the turntable and the plastic doo-dad that turns it.

The best I can do is trace it myself. Or I can send you closeup pictures of the two items I believe are high temperature cut off switches, there are very few numbers that could be part numbers or manufacturer icons on them unless on the 'front' side. I have not removed them yet to see. I could even test them to see (I have an ohm meter and a thermocouple temperature gauge). Though there is another sensor, I think for humidity, in the unit, but it plugs into the controller board. (The items I believe are high temperature cut off switches are in-line on the Load AC line before it goes to any other item in the unit)

I called Jenn-air and was told that since there are NO replaceable parts in the unit (that is complete bull), that a wiring diagram doesn't exist. I argued quite bit with the person that such must exist, manufacturing had to go by something to build the unit, she didn't budge. I haven't found anything on-line in a number of searches.

 

[rickgburton]

If you're the original owner and never had any service done on it before, the tech sheet and wiring diagram is still there on the machine. Remove the cover and look on the inside of the cover for an envelope. Follow L1 and N from the noise filter to the control board. If you have 120 VAC at the board when it shuts down, the board is bad.

 

[phillman5]

Found the problem

If you're the original owner and never had any service done on it before, the tech sheet and wiring diagram is still there on the machine. Remove the cover and look on the inside of the cover for an envelope. Follow L1 and N from the noise filter to the control board. If you have 120 VAC at the board when it shuts down, the board is bad.

1) I am the original owner, the tech sheet and/or wiring diagrams are not there.

2) I did another simple test: run microwave on counter top, and check the exhaust fan. Result: the exhaust fan does not run, but it is getting power. The symptoms match, runs great for short times, but on plates needing longer heat times it stops. So I am now petty sure the items I mentioned ARE thermal breakers and the unit is over heating on long heating cycles.

3) All is good, after a long discussion Jenn-Air is going to replace the unit even though the 1 year warrantee expired in January.

 

[rickgburton]

Cool. Whirlpool never replaces anything out of warranty let alone 6 months out of warranty. That must have been your lucky day!