Microwave does not heat but convection cooking works

I would suspect you have a failed cook relay on the control circuit board, but that can be economically repaired.

Details are here, along with a disassembly video.

see the next steps , use the VOM and fix it. God bless you

1. Check the power diodeThis electronic component is responsible for transmitting current in one direction. If the diode becomes defective it will cause your microwave to not heat. Test the diode and replace it if necessary.
   
2. High voltage capacitorResponsible for storing electricity, this part is a key component in any microwave. Remove, discharge, and test the capacitor to determine if it requires replacement.
   
3. Damaged magnetronResponsible for generating waves and producing heat. When your microwave is no longer heating properly, replacement will be required.
   
4. Thermal CutoffsExamine the thermal cutoffs on both the magnetron and the oven itself. Take off one of the leads and using a volt-ohm meter on RX1, check the terminals. If you get a result other than zero, replace the thermal cutoffs.
   

the Magnetron has gone (yes it's really called that) that's the part of the microwave that emits radio waves and cooks your food... 30 years ago when this tech (Microwave cooking) was new and expensive it was cheaper to replace that part than buy new... now it's the other way around... at least you still have a working electric convection oven.
it's very rare that a Magnetron go bad, so look for an old one of the same model and use that one for parts if it's that loved.

Hi,

Here is a tip that will help you to figure out what is wrong with your Microwave Oven....

Basic Microwave Oven Troubleshooting Tips

heatman101

/'/'/'/'/'/'/'/'/'/'/'/'

That is usually caused by a build up of fat from microwave cooking on the heating element. It will clear under normal conditions and return if one cooks foods like bacon etc, un covered to prevent splashing of the food that is being cooked.
Hope that helps.

If all appears to be running as its working but just no heat. Could be issue with magnetron. You could also have loose connections to magnetron or somewhere in high voltaged as well.

If the microwave side is not cooking, it may be the magnetron has died, if so, it may be expensive to repair and you may have to consider another purchase.

you need to buy a new one because it is broken.

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

The fact that the microwave and convection both do not heat indicated that the oven is in demo mode, check the user manual, otherwise it will possibly be a relay not triggering, may need a pcb replacement, check Demo mode 1st....Phil