The phrase "turning on the heat" typically refers to increasing the temperature indoors by using a heating system. Therefore, antonyms for this phrase would be any phrase that refers to decreasing or turning off the heat. Some antonyms could include "turning off the heat," "cooling down," "lowering the temperature," "stopping the warmth," or "quenching the heat." These phrases are typically used when the temperature is too high and needs to be reduced, rather than increased. So, when you're feeling too warm, remember to use these antonyms to help you cool down your surroundings.