Convection side of Microwave takes forever to cook.

If autocook is not working and everything else it, there is an issue with the sensor in the oven that detects the steam, The emission of steam is what triggers that unit to shut off. If it wont cook on any settings then the issue is with the microwave generator not putting out enough power. This could be from a lot of things.

Hello dutch.

This is an excellent microwave, over the range, white only. Here is a link to all of the features, and even the owner manual http://www2.panasonic.com/consumer-electronics/support/Home-Appliances/Microwave-Ovens/Over-the-Range-Microwaves/Technical-Specification/model.NN-S254WF.T#ts
Microwave Type: Over-the-Range Cooking Power: 1200 Watts Capacity: 2 cu. ft. Convection Cook: Without Convection Cook Dimensions Exterior Depth: 15 in. Exterior Height: 9.5 in. Exterior Width: 23.25 in. Miscellaneous Product ID: 22541798 More Information Details: Over the Range Microwave with Panasonic Inverter Technology provides true multiple power levels. When the user asks for 60% power, the oven delivers a true 60% power, not a pulsed delivery of 100% power 60% of the time. This method is called linear power delivery

Also the fact it is a convection oven could mean the oven temperature sensor is not picking up the oven temp. it is not telling the machine it is there by the board seeing its resistance, the unit will shut off as a safety feature. The oven sees temperature by reading the value of a temperature dependent resistor. As the temperature changes so does the value of the component ( oven temp sensor) that way the unit determines the temperature inside the unit. Sometimes those sensors will break since they are in the area with the heat and moisture, they get old and break.

I have exactly the same problem; always after 59 secs, it stops.

These installation instructions should help you.

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There are a couple of safety thermostats in the oven to shut down power if something overheats. One is on the magnetron tube (the microwave source), the other is on the cooking cavity. These sometimes go bad. There's also a power line fuse that may have failed, or become loose in its mounting clips. These can be tested with an ohmmeter; they should all measure very close to zero ohms if they're good.

Another possibility is that the control circuit board in the oven may have failed. I have worked on several Sharp ovens where the power transformer for the board has gone bad for no good reason. If the board goes bad the oven may appear to be dead as well.

Microwave servicing is best left to professionals. If you're thinking of keeping this one, take it to a service shop (or call for home service) and get an estimate. Then decide whether to repair or replace.

Hope this has helped a little. Thanks for using Fixya!

you need to remove the cover and after it operates and shuts down(CAREFULLY) feel the magnetron tube sides (BE EXTREMELY CAREFUL<HI_VOLTAGE ON TUBE FROM CAPACITOR) still, then if its not too warm there is a small temp sensor held by 2 screws on the side of the tube and they can go bad and shut off current to the tube,the tube will run warm, but should never run HOT,if its hot its defective

You can download that here free.

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

This may be due to the microwave section not working. Check the high voltage diode if it is ok, replace the Magneton.

if you have a warranty get a new one installed they have to honor your warranty or better yet if they want payment you want new unit sometimes they come deffective from the factory ad you may have gotten one of them