LOWER OVEN DOESN'T HEAT WHEN FAN IS SELECTED

Question

I have a BD62 Oven. The lower oven will not heat up when FAN OVEN is selected. When CONVENTIONAL OVEN is selected, the oven heats up.

I have looked at the dial switch, and cleaned the connections. They appear to be fine, and contacts are made.

Please can you advise me on which part is likely to be causing the problem.

I thought it might be the thermostat, however, I believe that is that was the case, the CONV OVEN would not work; or at least not cut out when the temperature is reached.

I appreciate that you cannot pin point the problem, but a pointer in the right direction would be fantastic.