What Does It Mean If Carrier Furnace Is Blinking Yellow Light?

You probably know by now that a blinking Carrier furnace is sending you a signal that it has run into a problem. Maybe the furnace is locked out, or one of the parts isn’t functioning normally. Perhaps a component is dead even. 

However, what’s the specific problem when the light is yellow? What could be the underlying problem, and how can you resolve it? Let’s dive right in. 

Should My Carrier Furnace Be Blinking?

No, your Carrier furnace shouldn’t be blinking when it’s running. As long as everything works smoothly, the unit will run without any blinking lights. However, anytime it begins to blink, there’s a problem. 

The reason it blinks is to alert you about the underlying issue. It helps to swing in swiftly to troubleshoot and ideally fix the issue before it creates a bigger risk.

What Does a Flashing Yellow Light on a Carrier Furnace Mean?

The yellow flashing light indicates that the furnace is stuck in high-fire mode. High-fire mode is a setting on the Carrier furnace in which the heater generates a lot of heat over a short period to “jumpstart” the heating process.

This is particularly necessary when the temperatures in your home are too low at the time the furnace kicks on. Engaging high-fire for a short period allows the furnace to raise indoor temperatures significantly over a short period before it goes back to normal function. 

High fire mode is usually 100% on most furnaces, though a few units can operate at up to 130% during high-fire. The bottom line is that it allows the furnace to raise indoor temperatures sharply over a short time, such as over a minute. 

At the same time, some furnaces don’t have a high-fire mode. If this is the case, you must wait for indoor temperatures to rise gradually. Fortunately, all Carrier models have this mode.

As you can tell, though, high-mode isn’t entirely safe for livability and furnace health, especially over long periods. Running the furnace at 100% capacity for an entire hour, for instance, would quickly result in overheating, affecting both you and the furnace. 

So, imagine if the furnace accidentally gets stuck in high-fire mode! It can be a terrifying situation. 

The flashing yellow light is a safety mechanism designed to alert you that the furnace is stuck in high-fire. It 

Reasons the Light on your Carrier Furnace is Blinking

The furnace can get stuck in the high-fire mode for several reasons. However, the leading cause is a defective gas valve solenoid. 

The gas valve solenoid helps control gas flow by using a plunger to open or close the valve, allowing the gas to pass or seal off the passage without leaks. They are primarily incorporated into gas heating systems for increased safety and efficiency. 

However, the solenoid can fail, thus refusing to open or close. If it refuses to close when the furnace is in high-fire, you’re in trouble. The blinking yellow light flashes to alert you to take action. 

What to Do if Your Carrier Furnace is Blinking?

Unfortunately, a gas valve solenoid stuck in high fire mode cannot be repaired. Instead, you need to replace it. More importantly, this isn’t a DIY job. Instead, you need to find a licensed HAC technician to help out. 

Carrier Furnace Error Codes (Others)

Carrier furnaces have many other error codes beyond the flashing yellow light. These include error code 1-2signalling that the blower is ON after the power-up and error code 1-4, a sign of ignition lockout. Others are error codes 2-1, 1-3, 2-2, and 2-3. 

However, the three most common error codes besides the blinking yellow light are 3-1, 1-3, and 3-3. So, what do they mean?

Carrier Furnace Code 31 Troubleshooting

Error code 3-1 (or 31) typically signals a problem with the pressure switch. The pressure switch is a unique electrical relay switch located adjacent to the draft inducer fan. It tracks air pressure within the inducer fan box, which helps determine when it’s unsafe to run the furnace.

If the pressure isn’t low enough to flip the switch, it’s usually a sign that the inducer fan isn’t removing exhaust gases at the desired rate. It’s dangerous to run the furnace in such conditions. So, the circuit will remain open, keeping the furnace shut. 

Solution: To fix error 31 codes, check the inner and outer condensing coils for duct and debris and clean the two areas. If the problem persists, reset the furnace. If it’s still blinking error 31, the pressure switch might be faulty. Replace it.

Carrier Furnace Code 13 Troubleshooting

Error code 1-3 (or 13) signals a limit switch lockout. The limit switch is also a safety mechanism built onto most furnaces. Unlike the pressure switch, though, it sits beneath the ducts in the furnace cabinet. Its primary purpose is to shut down the furnace if overheating is detected. 

You’re allowed to try to ignite the furnace again. However, if you try three times without success, the furnace will go into a lockout, a state in which the unit becomes unresponsive to external input until you reset it. 

Solution: The only solution here is to fix the underlying issue. Why is your furnace overheating? Is it a problem with the gas flow? Is it a damaged limit switch? After fixing the issue, reset the furnace and test to see if it works. Here too, we recommend professional advice as overheating is too risky to troubleshoot with DIY. 

Carrier Furnace Code 33 Troubleshooting

Finally, Carrier furnace code 33 (or 3-3) errors signal that the flame rollout switch has tripped. The rollout switch keeps an eye on the flame to ensure that it’s burning healthily and within the combustion chamber. The switch flips to prevent overheating and potential fires if the flame rolls out beyond the combustion chamber. 

The code is typically accompanied by a yellow flashing and essentially requires that you reset the furnace. 

Solution: Resetting the flame rollout switch isn’t too tricky. You can easily accomplish it without much knowledge of furnaces. However, the problem is the underlying issue. It’s counterproductive to reset the switch without addressing the cause. So, find out why your flame rolls out first and fix the problem. Then reset the furnace. You may need to engage a professional. 

How Do You Read a Carrier Furnace Error Code?

Carrier provides an elaborate owner’s manual to help users quickly decode the many error codes. 

Generally, the blinking light will display a two-digit number. The first digit indicates the number of flashes by the yellow light, while the second one is the number of green light flashes. We recommend noting down the numbers and cross-referencing on your owner’s manual to find out the meaning. 

How Do I Reset my Carrier Furnace?

Resetting your furnace is considered the first line of action if the unit is acting up. The rebooting process allows the furnace to resolve possible issues internally before it comes on. The best part is that it’s a simple process that you can complete in four easy steps;

  1. Turn OFF the furnace (both power and gas)
  2. Change the filter 
  3. Make sure the pilot light is ON. If not, fix it first.
  4. Now turn the furnace back ON.

Error codes can provide invaluable pointers when troubleshooting a furnace. Sometimes the error code alone can lead you to the underlying issue. Therefore, if you see your furnace blinking yellow, you need to act fast before the issue worsens.