Normal Operational Characteristics for a Microwave

It is normal to experience any of the following with a microwave or Advantium oven:


  • Steam or vapor escaping from around the door. This does not mean that the unit is leaking microwave energy. The door is designed to allow heat and steam to escape to prevent the overheating of the unit. It is normal to see some condensation between the door panels, unless the condensation does not dissipate within a reasonable amount of time.
  • Light reflection around door or outer case. The light is located outside the oven cavity and can reflect light out around the hinge, door, outer case, and oven lamp access cover.
  • It is normal for the door to have a little give in it, either up or down or in or out, up 1/8". This will not cause microwave leakage.

Lights and Sounds

  • Dull thumping sound or hum while cooking at power levels other than high. When using a power level other than HIGH or 10 the magnetron tube cycles on and off to obtain the lower power. This cycling of the magnetron tube causes this dull thumping, pulsating, or humming noise. When combination cooking in microwave/convection models, the cycling of the convection element and fan will alternate continuously with the hum of the magnetron and the fan.
  • Humming noise when the microwave is not in operation. The transformer emits a slight humming sound that is usually not noticed. The transformer is used to power the clock.
  • Flickering light under low voltage conditions.
  • The light will come on when the door is open, except for the JE635/835/1235 and JES636WK models.
  • A "clicking noise" upon startup is normal operation. This is found in models JVM1840, JVM1850, JVM1851, JVM1860, JVM1861.
  • On model PVM9005, the glass is tinted, so it can appear the interior light is not working. If you open the door and the light comes on, then the interior light is working normally.  
  • It is normal for the internal fan for the electronics to continue to run for a few seconds after the microwave cycle is complete, even if the door is opened.
  • It is normal to hear clicks or relays after starting the cycle. You will also hear them after pressing Start but before the unit actually starts running. 
  • The control panel buttons on microwaves are not backlit (do not light up).

Fan & Vent

  • A fan where the internal components are located will run continuously while the microwave is in operation to constantly circulate the air to cool the working parts. It is normal for the internal fan for the electronics to continue to run for a few seconds after the microwave cycle is complete, even if the door is opened.  This fan does not circulate air in the cavity.
  • Exterior fan noise on over-the-range models. The fan will make noise similar to a vent hood. Note: This fan is controlled by a high/low/off switch but will automatically come on if the cooktop surface transfers significant heat to the microwave. The fan will not go off until the microwave thermostat reaches a lower temperature.
  • Fan bearing noise. This will occur if the microwave is operated in temperatures below 50 degrees Fahrenheit. It is recommended that the room temperature be at least 50 degrees Fahrenheit for proper operation.
  • Warm outer case on the control panel side. The heat is normal and comes from the power transformer.
  • The Active Vent/Hidden Vent found on the JVM1800 series models will open during operation, and remain open as long as the microwave is running to keep the electronics cool during operation. It is also normal to hear a clicking noise as the "vent" opens and closes.

Warm Cavity or Case

  • Cooking foods in a microwave oven for an extended period of time can cause a heat transfer not only to the internal oven walls and floor, but to the external cabinet as well.
    • Exterior case may have symbol (triangle with waves) stamped in the metal.  This symbol means "Caution, hot surface".   
  • On over-the-range models, heat from the surface lights can make the cavity floor warm, especially if they are on for a prolonged period. This is normal.
  • Moisture or steam on the cavity walls during microwave cooking is normal.