There are a few common causes that are easy to fix when your air conditioner is blowing hot. First, check that your thermostat isn’t set to its heat setting and that the fan is switched “on.” Then, check your outside unit. If it looks clogged with dirt, leaves, or other debris, it could be affecting the cold air that it produces. The unit may also have lost power either at the breaker or because on an emergency shutoff switch.