Door light turns on when you start the machine but turns off a couple of seconds after that and the washer won't do anything. It's a frigidaire aft7000eg0. Any ideas.

Check if the lock is binding or the door switch is not being operated.

see this causes and fix it. God bless you
Door or Lid Latch Assembly If the washer lid won't lock the lid switch assembly might be defective. This is a very common problem. The lid switch assembly can fail either mechanically or electrically. Test any electrical switches with an Ohm meter for continuity. The switches should have continuity according to their design.

Door Lock Motor and Switch Assembly If the washer door won't lock the door lock assembly should be checked. The door lock can fail either mechanically or electrically. Test any switches on the door lock with an Ohm meter. The switches should have continuity according to their design.
Main Control Board If the washer door won't unlock the problem might be the main control board. This is not common. Normally the problem is with the lock mechanism.

this means that the door is not shut check to make sure the door button is still there its behind the door on the frame you should see a little black button sticking out if its not there you need a new door switch if its there try pushing the door button a couple times really fast sometimes this button gets stuck if that doesnt work its probably your door lock

Check to see if the door sags at all and doesn't line up correctly with the door latch. Then check to see if the drum wobbles when you rotate it yourself when not in use.

These doors are usually on a timer and so won't be released for opening until a couple of minutes have passed by after turning the machine off.

Assuming you've already allowed for this, try giving the door a good firm push (closing) on the mechanism. It may just have caught partially closed.

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Check your door switch. My dish washer would not work a couple of months ago, tore apart and messed with door switch and it has worked every since.

Hi, I've only just come on line to see and glad that you have identified the problem yourself- as you say persistence pays. I'm not even sure that I would have been able to suggest anything myself other than 'are you sure the lock and sensor are physically working?' ;-0) John C

It's a good machine. Well done for keeping it that long. It sounds like maybe it thinks the door is still open. (What happens if you intentionally try to start the program with the door open - It the result exactly the same? If it is, then it's probably the door interlock sensor.

If this is the case then you may find that a couple of good slams of the door will free off anything taht is sticking. Otherwise, you may have to check to see if there is a wire off the sensor (They do fall off sometimes) or.. after 13 years, it may need a new door sensor

If its showing a key symbol then the child lock is on.Press and hold the start/pause button in for several seconds and this should take the child lock off and start to work again.