Try the solutions suggested here first in order to avoid the cost of an unnecessary service call.
Nothing will operate
Has a household fuse blown, or has a circuit breaker
tripped? Replace the fuse or reset the circuit.
Cooling fan runs during baking or broiling
It is normal for the fan to automatically run while the oven is in
use or for some time after the oven is shut off.
Oven cooking results not what expected
Is the proper temperature set? Double-check the recipe in
a reliable cookbook.
Was the oven preheated? See "Baking" and "Broiling"
Is the proper bakeware being used? See "Bakeware"
Are the racks positioned properly? See "Positioning Racks
and Bakeware" section.
Is there proper air circulation around bakeware? See
"Positioning Racks and Bakeware" section.
Is the batter evenly distributed in the pan? Check that the
batter is level in the pan.
Is the proper length of time being used? Adjust cooking
Has the oven door been opened while cooking? Oven
peeking releases oven heat and can result in longer cooking
Are baked items too brown on the bottom? Move rack to
higher position in the oven.
Are pie crust edges browning early? Use aluminum foil to
cover the edge of the crust.