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Troubleshooting a Thermador Wall Oven F34 error code with ZERO disassembly


Samurai Appliance Repair Man

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You arrive on the call for Thermador wall oven. Complaint: F34 error code-- cooling fan rotation problem-- shown on the display when the oven is turned on. As a black belt in the martial art of schematic-fu, you pull up the schematic on your tablet computer. With one simple move, you identify the exact cause of the problem with ZERO disassembly. 

Question: What slick move did you make to identify the specific cause of the problem with ZERO disassembly? 

 

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41 Comments


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MarcusF

Posted

Open the door and notice lights aren't working because it's missing L2?

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MVrepairs

Posted

What is an HE sensor? 

I don't know how you could know exactly what it was without at least disassembling to the control board. Unless there is something obvious like what @MarcusF is saying, where you could see a leg was missing.

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MarcusF

Posted

5 minutes ago, MVrepairs said:

What is an HE sensor? 

I don't know how you could know exactly what it was without at least disassembling to the control board. Unless there is something obvious like what @MarcusF is saying, where you could see a leg was missing.

The legend at the bottom says HE = Hall Effect Sensor, so it's definitely related to some sort of fan, but it's a little unclear which one, and I'm also not sure how to test it without disassembling.

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  • Team Samurai
Samurai Appliance Repair Man

Posted

On 6/20/2022 at 12:54 PM, MVrepairs said:

I don't know how you could know exactly what it was without at least disassembling to the control board. Unless there is something obvious like what @MarcusF is saying, where you could see a leg was missing.

Which is it? 

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MVrepairs

Posted

i think it was fixed with the realization that the cooling fan runs off l2 and neutral and you checked the wall plug and found a bad neutral or no l2. 

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  • Team Samurai
Samurai Appliance Repair Man

Posted

 

12 minutes ago, MVrepairs said:

i think it was fixed

In the problem as given, there’s no fix… yet. Before we can even go there, we have to pinpoint the precise problem. Which can be done in this case. 

12 minutes ago, MVrepairs said:

you checked the wall plug and found a bad neutral or no l2. 

Can’t check the “wall plug” because this is a wall oven and the power supply is hardwired inside. So no plug. Wouldn’t bother with that in this case even if there was. No need. 

Neutral is not even in question here because I already have proof it’s good. How did I know that Neutral is good?

 

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Kendra jäger

Posted

My quick brain says turn on convection bake and see if cooling turns on, but I doubt that is the answer . 
following because I’m curious 

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  • Team Samurai
Samurai Appliance Repair Man

Posted

2 minutes ago, Kendra jäger said:

turn on convection bake and see if cooling turns on,

The cooling fan circulates air in the control plenum so it runs regardless of heat cycle selected. You're thinking of the convection fan. Does that help? 

 

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We know neutral is good because you were able to see the code 

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dondeck

Posted

pressing the convection option on the control would clear the L2 if the convection fan runs and would also clear the N. If L2 and N are good then it would be the cooling fan motor

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  • Team Samurai
Samurai Appliance Repair Man

Posted

2 minutes ago, dondeck said:

pressing the convection option on the control would clear the L2 if the convection fan runs

... AND if the convection element actually heats up. I'd want to see multiple L2 loads run... or not run... to be able to draw a conclusion. With multiple heating elements, it gets ambiguous to know which is operating without being able to see amps on those circuits. But then I have to disassemble. I'm too lazy for that. If only there were another L2 load that I could eyeball-verify....hmmm... O, who will save the laziest tech in the world from his quandry? 

Neutral is already cleared because: 

10 minutes ago, CLP said:

We know neutral is good because you were able to see the code 

 

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Vince Neibert

Posted

Try the halogen lights. The transformer needs L2.

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beyerappliance

Posted

Like above says, turning on convection bake and see it he convection fan would come on. That would clear N and L1, however, I believe it would only narrow it down to relay on control board or bad fan motor. 

If you fired up oven,  the cooling fan should start, If you hear humming, or slow fan you could assume bad motor, if you hear no relay click it would be bad board.

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  • Team Samurai
Samurai Appliance Repair Man

Posted

14 hours ago, beyerappliance said:

turning on convection bake and see it he convection fan would come on. That would clear N and L1,

Convection fan does not use L1. 

And no need to focus on convection. Lots of other ways to skin this cat. 

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  • Team Samurai
Samurai Appliance Repair Man

Posted

9 minutes ago, Vince Neibert said:

Try the halogen lights. The transformer needs L2.

What do I need to do to try the lights? Should I pop out one of the halogen lights and stuck my sniffer in there? 

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Vince Neibert

Posted

I’m not familiar with this oven, but however you turn the lights on that’s what I’d do. If they light up L2 is good. There are two of them. It’s unlikely both are bad.

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  • Team Samurai
Samurai Appliance Repair Man

Posted

On 6/19/2022 at 10:54 PM, MarcusF said:

Open the door and notice lights aren't working because it's missing L2?

That’s the spirit of a true lazy tech!

So I open the door and no lights. What do I conclude at this point? 

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  • Team Samurai
Samurai Appliance Repair Man

Posted

Just now, Vince Neibert said:

I’m not familiar with this oven, but however you turn the lights on that’s what I’d do.

The schematic tells you everything going on in the circuit, no special operation instructions needed. 

 

2 minutes ago, Vince Neibert said:

If they light up L2 is good.

What if the lights don’t come on? What do I conclude? Or can I conclude anything?  

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Vince Neibert

Posted

You got me there! I guess you could also have a bad transformer or a bad board

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  • Team Samurai
Samurai Appliance Repair Man

Posted

2 minutes ago, Vince Neibert said:

I guess you could also have a bad transformer or a bad board

With no lights and no cooling fan, both L2 and Neutral loads, inop, then I would need BOTH a bad transformer AND a bad board. How likely is that?

Instead, what’s my next move that may even fix the problem? 

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benstickell

Posted

Too small to see.. Could you just jump the relay for the cooling fan motor and see if it is working properly? Take an amp draw to verify against any spec given?

 

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  • Team Samurai
Samurai Appliance Repair Man

Posted

22 minutes ago, Vince Neibert said:

Flip the breaker?

That’s what I’d do!

In fact, that was the exact problem on this case. 

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  • Team Samurai
Samurai Appliance Repair Man

Posted

11 minutes ago, benstickell said:

Too small to see.

Really? You guys know you can click on the image for a larger view. It’s plenty big for detailed viewing.

12 minutes ago, benstickell said:

Could you just jump the relay for the cooling fan motor and see if it is working properly? Take an amp draw to verify against any spec given?

Way too much work! Remember, I’m the laziest tech alive. I’m too lazy to even open my tool bag if I don’t need to. 

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