You tried to shut down your Carrier furnace and restart it, but the unit only runs the blower immediately, blowing cold air without attempting ignition. If you don't know the reason behind this problem or what to do, don't worry. We have done thorough research to give you answers and possible solutions.
If error code 12 shows up, the system calls for heat when you power it up. It is normal because it is what it is designed for and supposed to do. Let it blow for 90 seconds, and the glow stick should start to ignite and produce flames. Then check for the error code after that.
If the problem is not solved and a different code pops up, read on to learn more about other possible causes and their corresponding solutions.
What Does Code 12 Mean On A Carrier Furnace?
Carrier furnaces have different error codes and blinking light patterns that you should be familiar with when you have a unit at home. The most common code that appears is the error code 12.
This code lets you know that the blower is on instantly after the power-up error and starts to push out of the system before it becomes heated. The fan should stop running after a minute and a half unless you turn on the furnace or turn up the thermostat to run.
It can also mean that the 120-volt AC power to the blower is interrupted during a power failure and requires cooling off to prevent further damage. If it still runs for over three minutes, check the thermostat's fan setting to see if it is set at 'on' and not 'auto.'
Considering this error is already solved, if another error code appears or the furnace doesn't ignite and produce no flames, try to examine other possible causes.
You can also watch this YouTube video to learn how to read error codes:
Why Is My Furnace Fan Running But Not Producing Heat?
Let's say you have resolved code 12, but the blower continues to run without heat. Usually, error code 33 starts to blink. The limit or flame roll-out switch is open and requires a manual reset.
You must check for a dirty filter or obstructed vent and duct system, inadequate combustion supply, and faulty switch and wiring connections.
Watch this YouTube video to learn how to diagnose and resolve error code 33:
Filter Change And Duct System Clean-Up
A clogged furnace filter and vents can prevent the furnace from generating heat, which is the most common cause of problems. Too much dirt impedes the airflow, which makes the heat exchanger overheat and shut off. As a result, your house won't warm up.
If you notice that the fan is still running, but there is no heat, it is better to replace the filter with a new one and clean your vents and duct system from falling out leaves and dust.
Your unit's manual can show you where and how to replace the filter. You should change cheaper flat filters at least once a month. As the manufacturer says, pleated filters can be good for three months. You should inspect them for potential replacement at least once a month.
Always remember to shut off the furnace and thermostat switches or do a total shutdown before changing the filters or working on your general clean-up.
A good filter will keep your air clean by removing particles such as pollen and dust from the air you breathe. Why not try this Filtrete product in various sizes to fit your furnace?
Check out this Filtrete filter on Amazon.
Gas Supply Check
Is your Carrier furnace not blowing hot air? This could be because you ran out of gas or someone accidentally turned off the gas valve and forgot to turn it back on.
Check your gas gauge and call your gas provider if it runs low. Otherwise, trace your gas line starting from the furnace meter. You should see a handle perpendicular to your gas pipe. Twist it parallel to your pipeline.
Faulty Control Board Inspection
If the problem persists, you must consider checking your control board and rebooting it. Use a voltage meter device to see that the electric wirings are still properly connected and have no current disruptions.
The control board has relays regulating the voltage of each component in the furnace. If the relay controlling the blower motor fails while it is closed, it will run continuously. Replace the control board if it is malfunctioning.
Another possible problem is that the furnace has a starting capacitor that isn't working. Dealing with messed-up electronics might be tricky, so it is better to call for a professional to let them do the job. However, you should expect a high repair bill.
Check out this Kaiweets voltage tester on Amazon.
Should I Let My Furnace Fan Run Constantly?
Continuously running your furnace fan is a good thing. Fans are designed to withstand continuous running, so you don't have to worry about premature wear or breakdown.
Whenever the fan is on, even if there is no heating in the furnace, it can still give an array of benefits. Here are some:
- Better circulation of heated and cooled air
- Prolonged lifespan of the furnace unit
- Less dust leads to improved air quality
- Reduce humidity level during cold weather
Why Won't My Furnace Blower Shut Off?
Your thermostat and fan limit switch tell your fan how long and when to start blowing the air. When the blower is still running and won't turn off when it is supposed to, most likely it is because of one of these problems:
- Faulty thermostat wiring
- Faulty fan limit switch that needs replacement
- Faulty fan limit switch is placed to manual override
Unfortunately, the first two problems are difficult to handle on your own, and you will need a hand from a technician. However, the last problem can be solved quickly by locating the white switch and pulling it to the setting, indicating the automatic mode.
Should I Let My Furnace Fan Run Constantly?
Continuously running your furnace fan is a good thing. Fans are designed to withstand continuous running, so you don't have to worry about premature wear or breakdown.
Whenever the fan is on, even if there is no heating in the furnace, it can still give various benefits. Here are some:
- Better circulation of heated and cooled air
- Prolonged lifespan of the furnace unit
- Less dust leads to improved air quality
- Reduce humidity level during cold weather
How Do You Stop A Furnace Fan From Running?
The furnace fan should only run when your thermostat is in automatic mode and during the heating cycle. But it is not normal when your fan continues to blow air whether or not your furnace is heating.
To stop the fan from running, you have to check if the thermostat is set correctly and then see if there are any fan limit switch problems.
When you set your fan limit switch to 'Auto,' and the fan still runs constantly, there must be a faulty thermostat wiring, or you must replace your bad limit switch. A professional is required to fix these problems.
Where Is The Fan Limit Switch Located?
The limit switch for heating a furnace ensures the furnace blower fan turns on and off at the right time. It should turn on when the thermostat needs heating for a few minutes and go off when the heat cycle ends.
This control also provides safety when the furnace temperature is too high. The fan limit switch is commonly located near the upper right corner inside the furnace panel cover.
However, the switch's location can also vary depending on the furnace model or whether the furnace is gas-fired or oil-fired. A silver or white cover will surround the controller.
Wrapping Up
You'll have to start the power again after a power interruption or shutdown. Usually, an error code 12 lets you know and confirm whether the furnace is working well. After a power-up, the blower will immediately run for about 90 seconds.
If the fan won't stop for a few more minutes or another error code appears, you must consider other problems. You need to understand error codes to take appropriate action. You'll need to consult your technician for complex electronic issues.
You can also read these articles:
New Carrier Furnace Noisy – Why And What To Do?