Microwave - Performance Test
If you think that your microwave may not be heating properly, there is a procedure you can use to check to see if it is heating as it should.
Follow the steps below to test the performance of your microwave:
Place a glass bowl (preferably a 2 quart glass measuring bowl) filled with 1 quart of water in the center of the microwave oven cavity. The water temperature must be between 59 to 75 degrees Fahrenheit (15 to 24 degrees Celsius).
Heat the water for exactly 2 minutes and 30 seconds on the High power level. The High power level is the default heat setting on the microwave.
A temperature rise in the range of 28 to 40 degrees Fahrenheit (15 to 22 degrees Celsius) indicates that the microwave oven is heating/cooking properly.
Should service be needed on your microwave, you can schedule a repair appointment with GE Appliances Factory Service.