Our Whirlpool under counter single Oven stopped working and showed no power. I tracked it down to the Thermal Switch behind the control panel and replaced that. It now works but the cooling fan does not come on (likely why the thermal switch went out).

The fan has three connectors going to it - red wire, black wire and a white wire (I assume 2 hot legs and the common). With the power on but oven not on there is no voltage to the red and black wires. When the oven is turned on I get 125 volts on the Red wire and much less on the black wire (it changes, is mostly around 2v but I think was about 26v when I first checked it with the oven on). I initially was thinking I would find 120v to each leg indicating the fan had failed and just replace it. Now I'm wondering (hoping) if it still could be the fan and only one wire (red) powers the cooling fan and the other wire is doing something else? Or, should both wires have 125v and something else is the issue and causing the black wire not to have the correct voltage.

The oven is a Whrirlpool- wos51ec0as04
The cooling fan part number is- w11245567

Any thoughts or input would be greatly appreciated.

Thanks