Air Conditioner Works But Not The Heat

Alexis Labadie Profile image

Written By:

Updated August 19, 2022

It’s never fun when, during the winter, you notice that your air conditioner/heater is not working. Chances are, you probably don’t know how to fix this other than calling in a certified technician for your top-notch air conditioner. There may be hope if your unit is a Sennville mini-split, but those come with their own problems, too.


  • You must maintain an HVAC unit to keep it working correctly, especially when it comes to cleaning and changing air filters.
  • Check whether you have tripped a circuit breaker or blown a fuse, causing your system to lose power.
  • Set your thermostat to “HEAT” and “AUTO” when you want to warm your house; however, it may not run until the temperature is five degrees lower than the setting.

Some common causes of your unit’s heater not working or the air conditioner fan not blowing can be easily remedied with some quick maintenance or troubleshooting steps. Read on to learn how to check for problems with your HVAC system.

When Your Heater Stops Working on Your Air Conditioner

Many people may not realize that their air conditioner also may also be used to raise their indoor temperature during the winter months. This misconception results from the commonly used term “air conditioner” for heating, ventilation, and air conditioning systems. However, many of the elements used to cool your house can also be used to heat it.

If you feel like your heater is no longer working, we’re going to discuss some common sources of problems for these units, including thermostat settings, power issues, and a dirty air filter. You may also be interested in learning what to do when your air conditioner keeps running when turned off, or when the heat is on while your air conditioner is running.

Dirty Air Filters

Performing maintenance on your AC system is vital for maintaining its strength and efficiency. Dirty coils or air filters significantly impact the appliance, blocking or eliminating the airflow. Air passes through different system elements to become hotter or colder, depending on the season and temperature.

Insider Tip

Set your thermostat to about five degrees lower than the current temperature to see if it will start.

However, if your air filter becomes clogged with dirt, allergen, or dust particles, the air doesn’t pass through as easily. A dirty filter may make it feel as though no air is being treated and released back into your house. If you aren’t sure how to clean these elements, check online or schedule regular maintenance with a certified technician.

Power Troubleshooting

For most AC or heating problems,‌ start by examining the power supply to your air conditioning system. For example, if you have blown a fuse or tripped a circuit breaker, you won’t have the necessary energy to start and run your AC. Check for these issues by looking at your circuit panel for anything that doesn’t match, like a circuit switch on the wrong side or a discolored fuse.

If the circuit breaker panel or fuse box looks correct, it could be another issue altogether. For example, a dead capacitor means that your AC unit won’t have the energy it requires to work. The capacitors store electricity, which provides the burst of power that starts and runs the unit’s motors, supplementing the electrical outlet’s output.

Thermostat Settings

Ensure your thermostat is set to “HEAT” and at your desired temperature, though you may need to turn it up if it is within five degrees of the setting. You will also want the fan set to “AUTO,” preventing it from running unnecessarily.

These settings should prompt the heat to run when your room cools past the five degrees below your desired temperature. Some thermostats will run if it’s only a degree or two off, so pay attention to your temperature settings. When you have the fan on “AUTO,” it should start and stop automatically depending on the temperature reading on your thermostat. If this doesn’t happen, you may need to call a maintenance professional.


Do not attempt to fix difficult thermostat or capacitor problems on your own; schedule a technician visit instead.


How does a furnace or heater work?

A heater works by blowing heated air through your home’s ducts that are released through vents. The type of heating used depends on the model of your furnace.

Why is my AC turning on the heater even on cooling mode?

Your thermostat may have a wiring problem that causes the unit to short out. A faulty thermostat or bad wiring can also cause this issue.

Why doesn’t an AC work without a compressor?

As the name applies, the compressor compresses air before sending it on through the system. If the air isn’t compressed, it won’t be able to go through the other elements.

STAT: Most homes, over 80%, use gas or electric furnaces. (source)

Alexis Labadie Profile image