Your air conditioner is blowing warm air because something is turning off the cooling system while the fan is running. Simple factors like thermostat settings and poor airflow may be the root of the problem, but there are also more serious possibilities like electrical issues and refrigerant leaks.

Make sure the fan is on auto and the thermostat is in the cool position. Additionally, it goes without saying that the set temperature is lower than the ambient temperature.

You should also check the filter in your air conditioner. Its purpose is to clean the air passing through the machinery of contaminants like dust. However, dust- and debris-filled air filters can completely prevent air from entering the system. The coils are then unable to remove heat. Therefore, the fan on your system simply blows heat back into your room.

Your hot water heater could stop working suddenly for a variety of reasons. The water heater tripping the circuit breaker is one of the most frequent. Your large appliances' circuit breakers may occasionally trip due to an unexpected power surge. Check the switch connected to your water heater at your electrical panel to see if it needs to be reset.

Your water heater's fuel supply being cut off is another frequent reason for breakdowns.

If you have a gas or propane water heater, the gas valve may have been shut off by someone. Your water heater cannot heat water without gas. Make sure the valve is set to "open" (parallel to the gas line, as opposed to perpendicular to it). If you notice a gas leak or smell gas (it has a "rotten egg" smell), you should immediately leave your house, call your utility company from a safe distance away, and have a professional repair your gas line.