Carrier Furnace Error Codes: What to Do in the Event of a Problem

When you own and operate your own business, it’s a given that there will be days when things go wrong. And while no one likes to think about what might go wrong with a piece of equipment, the fact is that failure is always a possibility. Let’s face it: no matter how well-built and well-maintained any equipment is, sooner or later something is going to give out on you. Any time you run a business, the risk of being caught off guard by some kind of mechanical failure increases. Fortunately, it’s pretty easy to recognize when something goes wrong with your Carrier furnace. In this article, we will examine some of the most common error codes you may receive from your carrier furnace, as well as advice on how to proceed to get things back up and running again quickly.

Error Code 12

In certain situations, an error code 12 could be an indication that there is a problem with your blower motor. This is one of the most commonly reported issues with a Carrier furnace. It’s important to note that the furnace will likely still be usable in most cases. You may simply need to lower your thermostat to compensate for the fact that the blower isn’t as strong as it once was. In some cases, a blower motor that is on its way out may also cause overheating issues in the furnace. If the motor is burning out, it may be struggling to draw enough power to keep the furnace operating at an acceptable temperature. This can cause the furnace to shut down to protect itself. Depending on the type of error code 12 you receive and the model of furnace you own, a blower motor issue may show up as a 12 error code, a 10 error code, or both.

Error Code 18

If you run into an error code 18, your thermostat may be at fault. Whether an older thermostat or a newer model, it’s not uncommon for thermostats to fail from time to time. Most thermostats will send an error code 18 when they are not receiving power and are therefore unable to properly regulate the furnace. When this happens, you will need to locate the thermostat and make sure it is getting power. If it is, the thermostat may have simply stopped working for no obvious reason. Depending on the model of the thermostat you own, you may be able to manually reset it to restore service. Bear in mind that thermostats are not designed to last indefinitely. You may need to replace your thermostat at some point.

Error Code 21

Error code 21 is another thermostat-related issue that may indicate a faulty thermostat, but it could also be an indication of a problem with the furnace’s built-in temperature sensor. If your thermostat is powered on but is unable to regulate the furnace, you may receive an error code 21. If the error code 21 is due to the sensor, you may notice that the furnace is running hotter than usual, regardless of the setting on the thermostat. If the error code 21 is related to the thermostat, the furnace would still be running, but it would not be responding to the thermostat. A faulty temperature sensor can be replaced, but it’s best not to try this yourself unless you have the proper training.

Error Code 24

If you receive an error code 24, it could mean that your furnace is not getting the level of voltage it requires for proper operation. Whatever the cause, this could be the result of a power outage, a blown circuit breaker, a problem with your circuit, a loose plug, or several other issues. Depending on your model and the type of error code 24 you receive, you may need to contact a professional to get things back up and running again. Depending on the severity of the problem, you may be able to operate your furnace for a short time. However, you should not rely on it for more than a few hours. If you need to run your furnace during a power outage, you will need to purchase an alternative source of power.

Error Code 28

An error code 28 could mean that your blower wheel is not rotating as it should. In some cases, however, this could also indicate that there is something wrong with the wiring in the furnace. If the blower wheel is not moving, the furnace will not be able to push air throughout your home. In addition, it could overheat as a result of not being able to expel enough heat. If the wiring seems to be at fault, you may notice that the furnace is on but not running. In either case, you will need to call a professional to address the problem. If the wiring error is due to improper installation, you may be able to resolve the issue yourself.


When you own a business, one of the best things you can do is be prepared for the unexpected. This means being aware of potential problems and being ready for them when they arise. It also means keeping tabs on your equipment so that you can identify potential problems before they become serious. Carrier furnaces are some of the most common types of HVAC units on the market, and they are also some of the most reliable. Even so, they are susceptible to a few common types of errors. When issues with your furnace arise, it’s important to know how to address them. This will allow you to stay in control of the situation and have a clearer idea of the next steps you need to take.