Usually when this happens that means the Magnetron has failed on the microwave. The mag is responsible for all heating operations on the microwave. The unit will even sound like it is going to power up in the first few seconds it is running but the mag will never engage.
what could cause this and is this normal the unit is about 4 years old . can i fix it myself
This is usually caused by a short in the magnetron itself. Power surges can weaken the coils over time but the ultimate failure is the amount of electricity passing through the mag during the cooking process. You can fix it yourself but you will have to be careful.
There is a high voltage capacitor in the unit that can hurt or even kill you if it is not allowed to discharge properly.
ok how do you discharge it
You can pull the plug on the unit and leave it unplugged for a few days OR locate the capacitor and, using well insulated needle nose pliers, touch both contacts with the metal. This will discharge the cap.
The magnetron is 115 dollars at www.searspartsdirect.com and the part number is XXXXX
That is kinda pricey considering the new units start out around 249.
thanks you've been great. War Eagle!!!