I have a emerson 8781 microwave, after two minutes of operation the unit shuts off. I dont recall hearing a fan noise. If i wait 5 minutes it can be run once again.

check the air filter and cooling fan.

Missy Uhland Bauman,

I understand that you are hearing a buzzing noise from your microwave, even though the door is shut and and it is not running. I would suggest to give the appliance a hard reset. You will do this by either unplugging it or cutting the power off at the circuit breaker for 3-5 minutes. After the 3-5 minutes, bring power back. If you are still hearing a buzzing sound, I suggest either contacting the manufacturer or your local authorized technician.

-Best Regards-

follow this test and fix it. God bless you

1. MagnetronIf your microwave is emanating high pitched or growling noises during operation, the magnetron could be going bad. Normally a nearly silent part, the magnetron uses high voltage and induces the frequency required to cook food. Although normally not a safety hazard to operate, this is a sign that the magnetron is failing and will need to be replaced as soon as possible.
   
2. Exhaust fan motorIf your microwave is making a very loud humming noise during operation, it could possibly be the exhaust fan motor. If defective the part will need to be replaced to silence the appliance once more.
   
3. Stirrer motorAnother leading cause of a noisy microwave is an expired stirrer motor. With use this part becomes worn and makes a loud grinding noise, which is usually a leading indicator that the part needs to be replaced. The stirrer is a metal blade that is slowly turned by the motor. This action disperses the microwave energy in a random pattern, which heats the food evenly. If the stirrer motor is determined to be nearing expiration, it should be replaced to halt the grinding noise.
   
4. Turntable motorA very common cause for a noisy microwave is a worn out turntable motor. This is a relatively easy repair and will put an end to the noise once replaced.
   

I would suggest you check the door switches inside the microwave oven just below the keypad, rectangular in shape. The switches are normally open or closed, set meter to ohms, unhook lead from one side and test with door open and closed. If readings are the same both ways the switch is defective. "check all switches"

Remove cabinet cover and observe what's going on.

I would bet that either your internal cooling fan is not running, or the magnetron is otherwise overheating.

We have a sound clip of what a microwave should sound like when the cooling fan and high voltage section are operating here.

It is vital that the cooling fan runs, or the magnetron will be destroyed.

Let me know if I can help you further.

We're happy to help you with free advice and we'd appreciate your thoughtful rating of our answer.

My daughter is having the same problem as you are having. Thing is we bought it for her new. She had not used it at all for a year. They finally bought a house, started using it in May. It is now doing the exact things yours is doing. Is there some kind of recall notice on these microwaves or what is wrong and how do we fix it?

If the mag overheats because its not being cooled it will shut down until its cool.

If the fan is turning slow you can try oiling it but it likely needs replacing.

Another thing that causes this is that the exaust port is blocked because its upagainst the wall and the hot air can not escape.

It may be as simple as a loose screw in the cover causing it to vibrate, or as serious as a failing magnetron.

While a microwave should never be left unattended, it's even more important when one is exhibiting a failure or any odd behavior.

So play it safe and stay with it while it's running.

It may be best to practice watchful waiting and wait until it fails "harder" or more seriously.

We're happy to help you with free advice and we'd appreciate your thoughtful rating of our answer.

Do you feel air flow? That's the key.

Most microwaves have the exhaust fan assembly at the back edge, not up front immediately behind the grille / vent.

Post back if you can give us more detail or have other questions.