Ventilation system on Jenn Air CVG4280

My Jenn-Air had the same problem. When you install the drip pan for the burner module, there is a "finger" on the pan that is inserted into a hole in the front of the stove. If you look into that hole, you will see a lever switch. The finger on the drip pan on the burner module is supposed to push that lever switch down and turn the fan off, but over time the lever gets pushed down further and ultimately it does not get activated when the drip pan is installed.

You can either replace the lever switch, or you can try to pull it back into place and tighten the two small screws that hold it in place. Actually, I chose a third option and attached a small, flat spring to the finger on the drip pan.