My new lg microwave with extenavent stays out does not latch in the closed postion.Had problem with it right out of the carton.

Okay. I got the Half Pint Microwave door off, opened it up, found the spring, used a Dremel to make a new point of attachment for the spring since the spring flang on the dooor was indeed broken. The door closes now and microwave turns on - but it doesn't stay on, unless I apply pressure on the top right corner of the door. So the latch is just slightly out of alignment. Will tinker with it some more. Maybe it's just a matter bumping up the lower part of the door a bit. Has anyone encountered this problem?

Latch or catch is either broken or misaligned. Find out which and repair or replace.

Hey Abraham Acevedo, thank you for the post!

From my understanding the door on your Frigidaire microwave, PLMV168, is not staying closed. You could be seeing an issue with either your door latch or latch assembly within the microwave. Since these components require patience and precision to replace or remove from your appliance, I always suggest seeking professional assistance. One must be very careful handling these replacement parts as they can lead to potential harm. -Matt

If you gently push up on the door latch heads (hook-like devices sticking out of the door) there should be spring tension. If they just flop right up, the spring is off inside.

Normally the problem is not the spring, but a broken spring mounting tab on the door latch head (hook) assembly or the inner door panel.

If it's the door panel, it's usually easier and cheaper to use epoxy and some kind of hardware to fashion a new spring mount.

The door latch head (hook) is easy to replace or repair if that's the issue.

The service manual for the R-408LS (the model you posted it under) is here.

You can order parts from the Sears Parts Direct Web site.

Going to be latch or latches and they have to be got at to replace, not usually a major repair for most shops. A lot of units where this is common a new and improved part will be supplied.

If the door is warped, buy a new microwave but that is very unlikely.
Release the lower hinge screws and square the door up to the latches then tighten the fixing screws.
Hope that helps.

It sounds like the light switch isn't being deactivated which is preventing the microwave from operating (a failsafe).
Look to see that the buttons inside the microwave (where the latches are inserted when you close the door) are actually being pressed.
They may be out of place, obstructed, or your latches on the door may be damaged.
If you don't see anything wrong, try pressing the buttons yourself (with a pen bottom) to see if the light goes off.

Its already solved!!!
Check the below link :-

http://www.fixya.com/support/t1064152-door_close


Thanks for using Fixya.

the door switch needs adjusting recommend a service tech to do this