An energon convertor is an aspect of Transformer anatomy that is comparable to a human heart.

Fiction

The Transformers cartoon

After destroying the robotic insecticide, which was the only way of destroying the Insecticon clone army, Megatron cynically said that the act broke his energon convertor which caused Starscream and Soundwave to laugh. Quest for Survival

Dreamwave Armada comic

Liftor's energon convertor once exploded on him. It was as unpleasant as it sounds. Armada #5

2005 IDW continuity

Energon convertors were not part of Transformers' bodies, but external devices used to turn useful materials into synthesised energon for their consumption. Cliffjumper used one while shipwrecked on Мир. Spotlight: Cliffjumper

After crashing on LV-117, Wheelie salvaged an energon convertor from his spaceship and carried it around with him. When an Arachnosaur attacked him, it bit into the convertor, was shocked by a jolt of energon and ran off. Wheelie later used it to power up Varta's ship, only for the vehicle to be stolen by Spectro and Spyglass. In order to deny the Decepticons of their victory, Wheelie took the safety catch off the energon convertor before they launched, causing the ship to explode. Spotlight: Wheelie