Some common problems of a convection microwave drawer, such as those manufactured by Sharp, include the microwave being loud or noisy, the display not working, or the appliance turning on by itself. Convection microwave drawers may be loud or noisy due to a broken magnetron or a worn out motor.
The magnetron is responsible for heating the inside of the appliance. Normally, the component runs silently, but as the appliance gets old, the magnetron can become worn out and begin to emit a high-pitched or growling sound.
A worn out exhaust fan, stirrer or turntable motor could also be responsible for the appliance making odd noises. The exhaust fan motor is responsible for operating the fan that vents the microwave, while the stirrer motor operates a metal bar that rotates on the roof of the appliance to deflect energy randomly throughout the appliance. Any of the motors can begin to emit a grinding sound when they are becoming worn out.
Defective control or display boards are responsible for the microwave display not working. Both components should only be replaced by a certified technician.
A convection microwave drawer that is turning on by itself most likely has a defective main control board. Another possibility is that the display's touch pad buttons are periodically touching one another.