[BB_TX]

If it is new, the odor may be the “new hot odor” smell. Not uncommon and usually fades over time. Common on devices using electric heating coils. Also some units have the convection oven exhausting the heat into a confined space behind the oven causing materials back there to become quite hot. If the odor is something new then there may be a problem with it.

If that central vac is on the same breaker as the microwave/convection there may be a load sharing device to prevent both operating at the same time to prevent tripping the breaker.