Thread: Thermador CT230 wall oven - blower starting by itself

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I also found info on another site that Thermador part number 35-00-091 has been superseded by Thermador part number 35-00-091RC, which has in turn been superseded by Bosch part number 368726.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.

Any advice?

Hi,

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.

Jake

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.

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).

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?

thanks