Exhaust fan comes on when burner turned on

Jenn-Air exhaust fan comes on every time the left two burners are turned on. It seems to work fine with right two burners. What's up with that?

The left side is set for your grill. There is apparently a switch under the left side top / front of the cooktop. The aeration tray has a prong on one end that fits into a hole in the front end of the burner basin and activates the switch which stops the fan from coming on when using the burners and allows the fan to run when using the grill. Try switching sides with the aeration trays as one might make better contact than the other.

The left side is set for your grill. This is normal.