March 15th, 2007, 09:36 AM
Thermador CT230 wall oven - blower starting by itself
I am helping my father troubleshoot a problem with his approximately 12-year-old Thermador CT230 double wall oven (CT-230-WC serial number 92050021). This oven has a blower that vents outside the house. The blower normally runs when the oven is on, and stays on after the oven is off until it cools down.
The CT230 exploded parts list is available on the Thermador web site.
The problem: The blower starts randomly, even when the oven is off. This is sometimes accompanied by clicking noises (the blower motor relay?). Once (but not every time) the lower oven display showed the error code E8. When the oven is on everything appears to work fine. The technician states E8 means to replace the "relay board" for that oven. I assume this is the lower oven thermostat control board part number 35-00-091. Unfortunately this part is no longer available.
I am trying to avoid spending unnecessary money, particularly if the oven ends up being junked. Questions.
1. I am looking for evidence of similar problems and fixes so I know investing in replacement parts is worthwhile. Anybody familiar with this problem?
2. The error code only appeared once. There are other parts than the control board that could be defective (blower thermostat, air interlock switch, for example). Is replacing the control board first advisable in this situation?
3. According to a parts list on the Thermador web site it appears the thermostat control board part number is 35-00-091. The vendor CG Industries LTD (http://www.cgiltd.com) refurbishes this part for $144 + shipping if you send it to them. Has anybody refurbished a discontinued part?
4. Are there any good sources for such discontinued parts, as an alternative to refurbishing?
5. I cannot find information about error codes for this oven. Any good source of this info?
Thanks for your assistance.
March 16th, 2007, 02:23 PM
Found error code list on this site
OK I feel like a dummy about question #5 - I found the error code list in a sticky message right at the top of the thread list. Not much help - E8 means "control board problem."
I also found info on another site that Thermador part number 35-00-091 has been superseded by Thermador part number 35-00-091RC, which has in turn been superseded by Bosch part number 368726. A few sites claim they can get this part but I am in doubt.
So I am still trying to decide whether to send the control board back to the previously mentioned CG Industries LTD (http://www.cgiltd.com) for refurbishment. I would hate to spend the money and not have the problem fixed.
March 17th, 2007, 09:37 AM
Don't feel like were ignoring you, but I myself don't have any experience working on Thermador products.
Hopefully another tech. or member that has good experience on this can assist you.
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March 19th, 2007, 06:52 AM
Planning to troubleshoot this weekend
Thanks - This same problem must have afflicted others. As of now the error code has not reappeared but whenever the oven circuit breaker is enabled the blower will run. Otherwise both ovens work fine. So I am not very confident the control board is the source of the problem.
This weekend I will take a peek at the guts. I think I can get to the control boards and wiring harnesses by just removing the control panel. Maybe I can spot a defective relay with my multimeter. I have the wiring diagram from the Thermador web site. But I don't think I can get to the blower guts (including the air switch) without pulling the oven out of the wall. It is a heavy double oven and my father thinks the external vent must be first disconnected by removing a panel in the cabinet above the oven. Not sure I want to get into that.
Thermador didn't do anything other than refer us to a local discount appliance vendor, who referred us to a technician. The technician would just replace the control board, if it were available.
May 18th, 2007, 10:23 AM
Troubleshooting results - bad clock/timer?
Unfortunately the problem has temporarily disappeared, so troubleshooting was not very effective. However I did learn something important after careful examination of the internal components and the circuit diagram. The blower motor is not energized by the control module so that is unlikely to be the problem.
The blower motor is not controlled by a relay. It can be directly energized in three ways.
1. Upper or lower oven selector is in bake, broil, or clean mode. The selector has both mechanical and electronic components. The blower is energized through the mechanical selector.
2. Blower thermostat trips. This ensures the blower runs to exhaust heat even when the oven is not on.
3. The clock/timer is enabled. The clock/timer is only used in clean and time/bake modes.
Because of the intermittent clicking sound I vote for a defective clock/timer (it contains relays). This component is number 21 on diagram #9 here.
CT 230 Part Diagrams
I have also determined that the air interlock switch is not in the blower circuit. That switch prevents the oven from heating if air is not exhausting. Not my problem.
I plan to do nothing until the problem recurs (i.e. the blower stays on forever). Then check the clock output voltage to see whether that is causing the blower to stay on. If so, I will replace the timer (<$100, and actually available).
March 16th, 2011, 12:19 PM
Can anyone provide instructions for removing front control panel and further detail to gain access to the controls in order to replace one of the controls?
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