Air Conditioner (AC) Works, but Not the Heater

Your heating system is most likely separate from your air conditioning system, although both are tied to the same thermostats for easier control.

The type of heating systems you have can vary depending on the region and climate where you live. For example, areas with colder winters may have a higher concentration of gas or oil furnaces, while regions with milder climates might see more heat pumps. Additionally, energy efficiency considerations and available energy sources can also influence the choice of heating systems. Before investigating why your AC works but not your heater, you need to know what kind of heating system you have.

The most common heating systems used in homes alongside air conditioners are:

• Forced Air Systems: Forced air systems are popular in many homes as they use a central furnace to heat air, which is then distributed throughout the house using ductwork. These systems can be powered by gas, oil, electricity, or even a heat pump. They are versatile and can provide both heating and cooling when paired with an air conditioner.
• Heat Pumps: Heat pumps are efficient heating and cooling systems that transfer heat between the indoor and outdoor air. They can extract heat from the outside air (even in cold weather) and bring it inside to heat the home. In warmer months, the process is reversed to provide cooling. Heat pumps can be standalone systems or combined with a backup heating source like electric resistance coils or a furnace.
• Ductless Mini-Split Systems: Ductless mini-split systems consist of an outdoor unit connected to one or more indoor units. They are a great option for homes without existing ductwork or for specific zones within the house. Ductless systems can provide both heating and cooling, making them a popular choice for heating and air conditioning.
• Dual-Fuel Systems: Dual-fuel systems combine a heat pump with a backup furnace, typically fueled by gas or oil. These systems are designed to optimize energy efficiency by using the heat pump during moderate temperatures and switching to the furnace when it gets extremely cold.
• Radiant Heating: Radiant heating systems involve installing heating elements in the floors, walls, or ceilings of the home. They can use electricity, water, or air as the heat transfer medium. While not as common as forced air or heat pumps, radiant heating is favored for its even heat distribution and comfort.
• Electric Baseboard Heaters: Electric baseboard heaters are individual units installed along the baseboards of rooms. They heat the air through electric resistance and are controlled by individual thermostats. These are commonly used as supplemental heating sources rather than whole-house systems.

If your air conditioning is working, but the heating function is not, there could be any of several potential causes for this issue. Some of these common causes are:

• Thermostat Settings: The first thing you should check is the thermostat settings. Make sure it is set to “heat” mode and the temperature is set higher than the current room temperature. Also, check the batteries in your thermostat if it’s battery-operated.
• Faulty Thermostat: The thermostat itself might be the problem. If it’s not sending the correct signals to the heating system, it may not turn on the heating elements.
• Circuit Breaker Tripped: Check your circuit breaker to see if the heating system’s circuit has tripped. If it has, reset the breaker and see if that resolves the issue.
• Dirty Air Filters: A clogged air filter can restrict airflow and cause the heating system to malfunction. Check the air filters and replace them if they are dirty.
• Pilot Light or Ignition Issues: If you have a gas-powered heating system, check if the pilot light is lit. If it’s not, you may need to relight it according to the manufacturer’s instructions. For electronic ignition systems, make sure they are functioning correctly.
• Gas Supply Issues: For gas-powered heating systems, there may be an issue with the gas supply, such as a closed gas valve or low gas pressure.
• Blower Motor Issues: The blower motor is responsible for circulating the heated air. If it’s malfunctioning or not working properly, the heating won’t be effective.
• Electric Heating Element Problems: In electric heating systems, if the heating element is faulty, it won’t generate heat.
• Ductwork Problems: Damaged or leaky ducts can lead to heat loss, reducing the system’s overall efficiency and heating capabilities.
• Safety Features: Some heating systems have safety features that automatically shut off the heating if a problem is detected. If a safety feature is triggered, the heating won’t work until the issue is resolved.

Some of these problems related to your AC working but not the heat can be troubleshooted on your own. However, given the potential complexity of heating and air systems and the importance of safety when dealing with HVAC equipment, your best bet is to contact a qualified HVAC technician to diagnose and fix the problem. They will have the expertise and tools to identify the specific issue and make the necessary repairs safely.