Should I keep the microwave turntable and plastic turntable support ring in the microwave oven when using convection mode? I am trying to operate a microwave convection oven for the first time. It is a GE Profile convection/microwave oven.  I am wondering if I am supposed to keep the glass microwave turntable and plastic microwave turntable support ring in the unit when I am operating in convection mode.  I know the first thing people will say is to read the owners manual, but the owners manual is extremely unclear. 

Here is a manual I found online, which is for a model very similar to the one I have.

On page 8 of this manual, as well as on page 8 of the manual that came with my model,  they discussed that the metal shelves should not be in the unit when microwaving food, but they don’t mention anything about the glass turntable and plastic turntable support ring  being used in convection mode. You might ask: why don’t I just remove these two items anyway when using convection mode just to be safe? The answer is that the support ring sits on a piece of plastic, and that piece of plastic seemingly can’t be removed, so I will still have to worry about plastic in the unit while using convection mode. So is that piece of plastic that’s part of the unit safe for the convection oven?
I cannot vouch for your specific GE oven, but I've been using my combination oven with the turntable and turntable support in Microwave, Convection Bake, Convection Roast and Combination Fast Bake for the last >10 years with no ill effects.

As your oven has the same technical capabilities as mine:


  Combination Fast Cooking
  Your oven also offers the option of Combination Fast Cook, using microwave energy along with convection cooking. You cook with speed and accuracy, while browning and crisping to perfection. 


I'm led to believe you're safe to use the turntable in convection only mode like I do as my round shelf fits perfectly on the glass turntable, so I never asked myself the question and have just used it like that since the first time I turned on the oven.