My Whirlpool Super Capacity 465 (RF380LXKQ) electric range is not heating properly. I used a digital meat thermometer suspended below the middle rack to check temperature. This way I could have the display outside while the door was closed.
When set to a temperature the preheat indicator comes on and the oven counts down the time till ready. However when the time hits zero it is not at the proper temperature. If I set it for 400F it will only be 300F when the time ends. If I raise temperature to 415F it will eventually settle out around 400F.
I tried using the Oven Temperature Control adjustment in the manual but the amount that it is off by changes with temperature. In order to get it to settle around 450F I had to have the oven set to 470F.
Any suggestion on what the problem is / how to troubleshoot it? I really don't want to buy a new oven.