I have Whirlpool Accubake System electric oven, the top works fine but the oven doesn't achieve the correct heat. When set to 350 degrees it only reaches approx. 250 -260.
I bought an oven thermometer to check it. To get to 350 or 400 I have to use BROIL not bake.
Pull the range out of the wall. Remove the rear panel and check the oven temperature sensor for continuity. Normal reading at the room temperature suppose to be about 100 Ohms.
If the reading is incorrect, replace the oven sensor.
If the reading is correct then the problem is a bad control board. This part has been discontinued. In such situation it is time for a new range.