Kenmore Elite Oven 790.48089000, Not Heating

[BillHammer]

Blasted Oven, make no heat. Controller alive and (seemingly) well, shows/sets time, aux functions like lights and fans and whatnot work great. Call for heat, or broil, or convect heat? Nada.

Breaker off, opened that sucker up and pulled the tech sheet. No smell of burning. Found the common part is the mechanical thermal circuit breaker. Looks like it should be closed during normal operation, cause power gotta get to the elements. Yanked one lead. Got the trusty Fluke Oh look.. 3.62 megohm. Hmmm.. that's kinda open, I think maybe.

So, before I order a new one, I pull the other lead, clamp the 2 browns together nice and shorted - should work now for a quick test, right?

Powered up. Nothing. 100 degrees. No bakey, no broil, no nada. Sat there for maybe 5 minutes in case the electrons were slow today. :)

WTF?? Bad thermal breaker AND bad relay board?? Or just the ghost of Sears making me want to buy Whirlpool?

Thanks,

-Bill

[ServiceTech_Daniel]

What was your voltage measurement at the terminal block? did you have 240 ?

120 from L1 to Neutral and 120 from L2 to Neutral?

 

 

[BillHammer]

Which terminals? Which block? (Sorry..)

[BillHammer]

One more - measure this with heat off, or bake or broil on?

[BillHammer]

Never mind, I found it. Yes, 2 legs of 120, both hot, 244 VAC across the inputs to the elements. Neutral fine.

[ServiceTech_Daniel]

Hey @BillHammer sorry for the late response , i didn't get a change to get back online . Sorry i should have clarified which terminal block, but looks like you found it . 

From everything you have said so far it sound's like you have a bad PCB control , If you have the schematic , i would test the voltage coming out of the board to the elements (With the bake on, or broil on) if your not getting any voltage you have a bad PCB , if you do have voltage coming out, you will need to find where you are loosing it (broken wire, thermal cut off , ect)

 

[BillHammer]

Ok, good power into the relay board, but the power relays for the elements are just not switching. So, ok, bad PCB. All the low power stuff is fine..

This looks like a relay board mounted on top of a control board. Do I just get that one and replace it? Or both boards, is it all considered 1 unit?

And, the thermal breaker is bad, too. Can't be 3 megOhm when cold. We had some electrical storms, wonder if they hurt things.. But, I have a whole house surge protector, if that matters.

[BillHammer]

Need to know where I can get the thermal breaker and relay board, part numbers, etc.

[BillHammer]

Last item. The thing I thought was the thermal circuit breaker is apparently a limit thermostat for the cooling fan. Got a pic of it inside the case and looked up the number. Odd, though, I don't see it on the schematic and if I pull one lead the fan still runs. I have no idea what is going on.

BUT - I used 2  pieces of 12 gage to jump past the relays on the board, P1 to P3 and P5 to P9, right at the control board. That should have put 240 vac across the bake element, and indeed, it heated. So, whatever or wherever the thermal breaker is, it's fine.

The control board seems to come as a single unit. It's expensive($400) though, not sure if it's worth it, oven is 12 years old.

Am I on the right track? Would you buy a board, or get a new oven?

[Vance R]

4 hours ago, BillHammer said:

Am I on the right track? Would you buy a board, or get a new oven?

Yes as far as being on track.  When call for heat do you hear the relays click?  If you hear the relays click the next part depends on how much you want to diy.  You can remove the printed circuit board with the relays - the daughter board and check the solder connections. If it is cold solder joints just resolder the connections. If the relay is burnt you can replace the relay. You can send the board out to be rebuilt for less cost. Last replace with a new module - both printed circuit board and frame are just 1 part number.