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Troubleshooting a Thermador Wall Oven F34 error code with ZERO disassembly

Samurai Appliance Repair Man

Entry posted by Samurai Appliance Repair Man in Tech Talk

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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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Vince Neibert

Vince Neibert

Posted

Thanks for the excellent training exercise. I violated my own long standing rule-“Start with the easy stuff”. With all the hi tech it’s easy to overlook simple problems.

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Samurai Appliance Repair Man

Samurai Appliance Repair Man

Posted

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19 minutes ago, Vince Neibert said:

Start with the easy stuff”

Yes but remember you only knew to flip the breaker because 1) you read the schematic and 2) based on that, cleverly chose another load to test to verify that you were missing L2. Only then did you know to flip the breaker. There was a lot of front loaded work— real work— that went on between your ears to make that action. That’s why we makes the big money! 

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tcmeyer14

Complaint: F34 error code-- cooling fan rotation problem. I'd turn on the oven and feel the airflow. 9 timesout of 10 the cooling fan is the problem usually a build up of dust and grease on the squirrel cage or fan blades slowing it down. 

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Quick

Awww heck should not the complaint have been no heat? Trickery I tell you. Trickery. 🙃

 

 

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PCEtech5

PCEtech5

Posted (edited)

2 hours ago, Vince Neibert said:

Flip the breaker?

That’s my go to move on malfunctioning wall ovens.  After I’ve pulled any error codes, I cycle the power to see if there are any changes at all.  Control board could just be having a moment, or it could be something else.

Went to a job one time and the first thing I asked the customer was where the breaker box was.  Within 2 minutes I fixed the issue.  They weren’t to excited about paying the service fee.

Edited by PCEtech5
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Samurai Appliance Repair Man

Samurai Appliance Repair Man

Posted

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18 minutes ago, Quick said:

Awww heck should not the complaint have been no heat? Trickery I tell you. Trickery. 🙃

 

 

Typical customer problem report. They see weird stuff on the screen and that’s all they can think about. Any other functional descriptions get drowned out in “all I wanted to do was heat a frozen pizza. Whaaaa!”

Has happened to me more than once lately. That’s why you start with their problem statement but you still have to get eyeballs on the machine and see the rest of the story.

Typical customer trickery!  

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ecappliancecompany

ecappliancecompany

Posted

fan to dirty to  operate correctly try to clean the oven, if this happen after a  electrical surge or autage turn off dedicated circuit for 1 hr

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ApexSamuraiTech

ApexSamuraiTech

Posted

Put the oven into convection 1st, verify the fan and the element turn on. L2 present. Then, second put the oven into self clean - verify function. Looks to me like the convection relay is supplying power to the cooling fan relay and they all three most likely share neutral. If self-clean and convection both work then the fan motor is not working.  Verify by looking for switched power 120vac at P6, with convection oven turned on. If it is not present bad relay board. If it is confirmed - bad fan motor.

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Vince Neibert

Vince Neibert

Posted (edited)

12 hours ago, ApexSamuraiTech said:

Looks to me like the convection relay is supplying power to the cooling fan relay

I don’t see that is the case. All three of those relays receive L2 directly. Could be a bad relay. I think your confirmation test will work, but I think you could put it in normal bake and achieve the same results. Of course you would want to test on both sides of motor with LoZ function.

Edited by Vince Neibert
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Samurai Appliance Repair Man

Samurai Appliance Repair Man

Posted

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19 hours ago, ApexSamuraiTech said:

Looks to me like the convection relay is supplying power to the cooling fan relay and they all three most likely share neutral.

Try expanding the image. This is clearly not the case. All three motor relays are in parallel circuits with independent paths to L2. The convection relay is not supplying the cooling relay. Each motor has its own relay. The relays are switching L2, not Neutral. Electrically, L2 supply to the motor relays is identical to L2 supply to the elements— both L2 supplies look the same to electrons.  

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Jamesbrusseau

Jamesbrusseau

Posted

If you hear the fan running, then that means your sail switch could be not working or has failed and needs to be replaced.

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Samurai Appliance Repair Man

Samurai Appliance Repair Man

Posted

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24 minutes ago, Jamesbrusseau said:

then that means your sail switch could be not working

Where do you see a sail switch in the schematic? 

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Peter Graber

Peter Graber

Posted

Rookie tech here....what does flipping the breaker tell you in this case? (I am assuming you mean flip off and then flip on)

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Vince Neibert

Vince Neibert

Posted (edited)

41 minutes ago, Peter Graber said:

Rookie tech here....what does flipping the breaker tell you in this case? (I am assuming you mean flip off and then flip on)

Your assumption is correct. The purpose is to reestablish the internal connection in the breaker for L2 in this case. The contacts inside a breaker can pit and burn over time preventing current flow. Turning the breaker off and on can often times restore the connection. We didn’t know up front this was the case, but flipping the breaker was a first step(which worked in this case) before resorting to any tear down of the oven.  

Edited by Vince Neibert
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