A blowing machine for containers, in particular bottles, with a preform heating module, to which a blow wheel is assigned and which contains a conveyor chain with exchangeable heating mandrels and optionally exchangeable shielding plates, with a service area provided on the conveyor chain in the heating module, in which an automatic changer for the automatic changeover of at least the heating mandrels is arranged. The automatic changer includes a magazine holder, a turret, which is adjustable and rotatable between the magazine holder and the conveyor chain, with grippers, and movably drivable unlocking components for engaging locks.