PVM1870SM3SS microwave active vent will not close after opening

My initial guess is that the thermo fuse is blown. Simple to replace, only need a Phillips screwdriver. Heres a YouTube video describing how to proceed.

https://youtu.be/HV4SJA-_N_c

Hi,

This part is a Cabinet fuse and will stop power to the control panel, works through L1. This open or fails when the microwave cabinet get too hot and it is protecting itself.
So yes to your question.

I hope this helps

I’m happy to help further over the phone at https://www.6ya.com/expert/gere_bf68e6055dd61249

A door switch or two are bad and it took out the main fuse.. Change the door switches and fuse. Get the correct parts and make sure you get the switches in the proper locations and configuration

Either a mechanical or electrical issue at the vent.

I had GE look at the problem today (my microwave is less than a year old and under warranty). He replaced the cam louver and that seems to have fixed the problem. This is a small motor accessible by removing three screws and the active vent door. The whole visit was less than 15 minutes.<!-- from fixya rte -->

I have this same problem occasionally. Pull the vent grill open and look for a white cam that rotates when the microwave is on. To the right of that cam, there are two gray switches. The bottom switch should have a red tab that pops out. When the vent grill opens and closes continuously, the red tab is stuck in. Take a flat screwdriver or tooth pick and push gently in on the red tab to release it. It must get stuck due to grease or dirt accumulation. Good luck.

Interesting post, because I have the same problem! I have spent the better part of today researching and taking our microwave apart (partially) to inspect the top portion re: outside vent. Everytime the microwave is on, the "active vent door" (manufacturer's term, not mine!) opens. Apparently this is normal. But it also opens when you turn on the vent fan, when cooking on the stovetop. I don't like this feature, because I think it 'overrides' the outside venting system. I double checked our outside vent to ensure that when this oven was installed, the person did in fact allow the flap to be open when the fan is on (he did). So I think what 'our' problem is, is that the microwave active vent sort of interferes with the outside vent, thus more of the cooking smell being blown into the house instead of the outdoors. I was thinking of simply disconnecting the gizmo that make the active vent door open each time you use the oven and/or vent fan option however I don't think that's a good idea as apparently the main purpose of the active vent door is to keep the electronics of the microwave oven from overheating. The more I read about this version of microwave, the less impressed I am with it. Lots of electronic issues with it. I am not fussy either with having the microwave over the cooktop. Sorry I don't have a solution for your problem but I do feel your pain!!!

Yes, this microwave will vent either out through the top or the back. A damper will be needed if it was not saved when the unit was installed. A list of other items are listed in the installation instructions at this link To GE.
http://products.geappliances.com/MarketingObjectRetrieval/Dispatcher?RequestType=PDF&Name=49-40409-1.PDF

When the unit begins the never ending opening and closing cycle, turn the vent fan on for a few seconds and then turn the fan off. This seems to stop the active vent from opening and closing. If this is GE quality, this is the last thing that I am going to purchase. GE refrigerators are garbage and now I am having problems with a new microwave oven.

A simple test is to place a piece of bread in the microwave ( it heats up very fast) and then if your microwave was actually ON and generating RF, the bread would get hot very fast.. If it remains cool then only the fan is on. It appears that you may have a faulty door switch thou because once you open the door, your microwave should be off..

Are you sure the VENT is not on? That blower will operate regardless of the door open or closed so you must switch it OFF.