My car smell antifreeze when I turn the heather on. on 2004 Chevrolet Trailblazer

the first time I try to turn my car on but fail my brother push the gas pedal and turn on the engine start working but after that my car start smelling like burning, when I start driving smell antifreeze I thought there was a leak somewhere but I did not find anything, the internal leaking could be inside the motor?

maybe your heater core is starting to leak