GE Prfile microwave heats sometimes

[slowgin]

I have a JE2160SF03 microwave if we use it for 2 minutes or less it will heat, if we try to cook anything longer then that, it no longer heats.  I have searched but can't find what I need to replace.
 

[tgoods]

Can you hear the cooling fan running?  If not, that's your problem.  The magnetron overheats and trips the thermal limiter.

[slowgin]

I just checked and it is a built in, and once I turn it on I can feel a lot of air coming out.  What else can I try?  There is no loud noise or strange noise while running.

[tgoods]

Pull it out and set in on your counter.  Plug it in and see if it works.  If it does, then I would suspect a problem with the installation, not enough airflow.  If it's still not heating, you have to pull the cover.  I hesitate advising pulling the cover on a microwave because there is lethal high voltage in there.  Even when unplugged the HV capacitor can hold a deadly charge. If you still want to pull the cover, let me know and I'll tell you what to do.

[slowgin]

I pulled the Microwave out and put it on the counter and put a small potato in for 5 minutes, it was only warm when I picked it up, same as when it was in the wall.  Ok, so next is to take the cover off and then look for or do what?
 
I don't know if it matters, but it stopped working correctly one day right after we were cooking 6 potato's for 10 minutes.
JE2160SF03

[JWWebster]

Their is a wall of holes behind the microwave. They get clogged with lint and grease and the mag overheats, the limit trips.

[slowgin]

I have looked at all of the holes in the unit for anything that is dirty, I have taken the cover off after it was left unplugged since yesterday.  There is nothing that is dirty that needs to be cleaned.
 
Now that the cover is off what do I need to look for?
 

[JWWebster]

Look for a failed fan motor, something has to keep the mag cool or it will trip the limit.

[JWWebster]

http://www.gunshowminute.com/mwd/advantium_sca1000_sca1001_sm.pdf

[JWWebster]

Page 11:
Magnetron Fan
The magnetron fan operates in all modes of
cooking (Microwave, Speedcook, and Oven/
Bake), even when microwave energy is not being
used. Room air is drawn in through the upper grille
area and into the magnetron blower area. The
magnetron fan blows the air through and around
the magnetron tube and the other components in
the magnetron area

[slowgin]

My unit has only one fan I have attached a picture.  This microwave has a trim kit it is not the one with the exhaust fan above a stove.
The one fan that it has still works, I see the Magnatron but do not see a fan on it.

[tgoods]

Nice picture.  If you have an ammeter, clamp it around the black or white power cord wire.  Put a glass of water in it and turn it on high for a few minutes.  You should get a reading of about 15 amps.  If you don't have an ammeter, listen for the magnetron to kick in.  It's a slight buzz you hear about a half second after you start the microwave. If the amperage drops out or the mag quits buzzing, immediately unplugged the microwave and discharge the hv capacitor.  Check the thermal limit mounted on top of the magnetron, it should have continuity.  If it doesn't have continuity, your magnetron is overheating for some reason.

[JWWebster]

The fan for the magnetron is that big thing to the right of it with a motor attached to it and directly behind that is the holes I was talkin about. The black klixon on top of the mag is the high limit. It might be weak and tripping after 2 minutes. I doubt it though. The thing looks pretty clean to me. Is that fan blowing pretty strong? That type of fan motor is a 3000 rpm so it should kick up some air in there.

[whirlpooltech]

Watch out for the high voltage.
Even when the microwave is unplugged the capacitor can still store high voltage in it.