What Is Code 34 On Carrier Furnace?

You need a fully functioning furnace during the wintertime. And having your Carrier furnace flash error code 34 should alarm you. But what does this error code mean? So we researched what it indicates, and here is what we found. 

The carrier error code 34 indicates a failed ignition test. This indicates that the furnace control board has shut down because it did not detect a flame or an appropriate flame.

Continue reading as we provide you with the signs and symptoms that your furnace is experiencing this error code. Additionally, we'll discuss what causes this error and how to fix it. We'll also cover other error codes you might encounter and how to fix them. 

House Heating Unit Repair by Professional Technician, What Is Code 34 On Carrier Furnace?

What Are The Signs That Your Furnace Is Experiencing Code 34?

There is probably a problem with the proving of flame when the furnace begins and shuts off after 20 to 30 seconds. To prevent filling the house with unlit gases and inflicting soot damage to the appliance, a furnace checks that the combustible gas is lighted before turning on.

Flames may be visible before the appliance turns off after 20 to 30 seconds. If the gas delivery to the burners is the issue, there may be no flames, and the furnace may turn off after 20 to 30 seconds.

What Causes Your Carrier Furnace To Flash Error Code 34? 

These are the most common causes that why your furnace is experiencing this error:

  • Flame Sensor Soot Buildup
  • Manually Turning Off the Gas Valve
  • Gas Pressure On The Inlet And Outlet Is Low
  • No Ground Controls
  • Malfunctioning Gas Valve
  • Improperly Grounded Flame Sensor
  • Dirty Burners

How To Remove Flame Sensor Soot Buildup?

Remove the flame sensor, then thoroughly wipe it with regular steel wool to remove any remaining soot. It is advisable to get a new flame sensor as a backup since they are reasonably priced and can ultimately break down.

You can check out this article to know where the flame sensor of your furnace is usually located: Where Is The Flame Sensor On A Carrier Furnace?

What To Do When You Manually Shut Off The Gas Valve?

What To Do When You Manually Shut Off The Gas Valve - Pipes and valves of a heating system

Ensure that the gas shutoff valve is activated on the gas line leading to the furnace. Confirm that the valve's On/Off switch is securely in the ON position.

How To Fix Low Inlet & Outlet Gas Pressure?

House heating system with many steel pipes, manometers and metal tubes, selective focus

To diagnose if you have a low inlet gas pressure, you can do the following: 

  • Use a manometer to check the gas valve for adequate gas pressure. Propane will have a water column of 11–13 inches, but natural gas will be 5-7 inches.
  • You can tap into the gas valve's incoming side to check the pressure there. You can use a gas pipe cap with a drilled hole that will receive your brass manometer fitting and read it at the output if your valve lacks an incoming tap or is broken.
  • To fix incoming gas pressure issues, get in touch with your utility company or propane supplier.

On the other hand, to check for pressure at the outlet, you should: 

  • Using a manometer, check the gas pressure by unscrewing the gas pressure tap cover and fastening the manometer.
  • After connecting, turn on the furnace and adjust the set screws for High Fire and Low Fire settings as necessary.
  • The set screw can be rotated clockwise to raise gas pressure or counterclockwise to decrease gas pressure.
  • Apply a little amount of pipe dope to the test connection cap after adjusting, then reinstall the gas valve.

What Furnace Controls Should You Check To Ensure That They're Grounded?

Examine the safety of the ground wire leading to the gas manifold, usually a green or green/yellow wire, as well as the ground at the blower motor, inducer, and transformer.

How To Tell If You Have A Defective Furnace Gas Valve?

How To Tell If You Have A Defective Furnace Gas Valve - Servicing a gas boiler of a heating home system

If the gas valve is receiving 24V at the point of incoming power but isn't opening, the gas valve is broken. The internal valve's control solenoid most likely failed.

How To Clean Dirty Gas Burner?

How To Clean Dirty Gas Burner - kitchen gas cooker with burning fire propane gas

You must take the following actions to clean the burner on your gas furnace:

Step 1: Disconnect The Gas

When performing any furnace maintenance or cleaning tasks at home, safety should always come first. Before beginning, always switch off the gas and power to your appliance.

Step 2: Take The Burner Out

You must take the front panel off your furnace to find the burner. For instructions on how to remove the panel, read your owner's handbook. The burners should be visible in the chamber above the blower.

Step 3: Clean The Burners

You will want a vacuum with a delicate brush to clean the burners. Any debris on the burner should be removed using the vacuum. Rust and dust manifest as debris. To remove any debris, you might need to lightly tap the burners.

Step 4: Place Back The Burners

Now that your burners are clean, replace the panel after putting them back into the furnace. You can now restart using your furnace by turning on your gas and electricity.

How Do The Lights In Your Carrier Furnace Indicate An Error Code?

Your Carrier furnace will notify you if the system ever experiences a fault. Although the fault codes for furnaces differ depending on the model, the majority of the widely used furnace brands all convey problem codes via a system of flashing lights.

Find the LED light, then observe how it blinks to decipher the furnace error code. Take note of the frequency and duration of the light's flashes. For information on what each combination of lights signifies, consult the installation handbook for your particular furnace.

Usually, a two-digit code is used to accomplish this. The first number represents the number of yellow light flashes, while the second represents the number of green light flashes.

Typically, a green light means that everything is operating as it should. A fast flashing green light, for instance, could indicate that the blower system is operational, which means that the furnace is providing heat to the house at the moment.

What Are Other Carrier Furnace Error Codes?

If you're wondering what other error codes you might encounter with your Carrier furnace, we listed some of them for you and how to fix them. 

Blower On After Power Up (Code 12)

This indicates that the blower begins to force air out of the system before it heats up. Typically, the blower fan should only turn on 90-180 seconds after the thermostat signals a need for heat.

To fix this, make sure the thermostat is set to "on" rather than "auto" for the fan. You might have unintentionally linked the fan wire to the heat terminal or wire.

Also, check the thermostat's back; if you have a gas furnace, it needs to be set to "gas heat."

Switch Lockout For Limit Or Flame Roll-out [C0de 13]

The blower assembly of the unit is activated and deactivated by the limit switch. The flame rollout switch is a safety mechanism that will cut off the gas valve if it senses flame rollout.

Once the unit has cooled down, it will frequently reset itself. If not, you may need to replace the fuse link, which acts as a flame rollout protection device, or reset the switch.

Ignition Lockout[(Code 14]

Your device had recognized a dangerous condition if it had experienced an ignition lockout. The controller then turns off the electricity and gas.

In this case, your furnace needs time to cool down. Typically, the furnace will automatically reset in 3 hours, so you just need to wait for it. 

Gas Heating Lockout [Code 21]

When this happens, the furnace turns off the electricity and fuel to prevent harmful operation.

To fix this, examine the gas valve. You may need to replace the valve if you don't hear a clicking sound when you switch the appliance on. The control board may also need to be checked.

Abnormal Flame-Proving Signal [Code 22]

This indicates that the gas valve is turned off, yet the flame is still there. The gas valve could be blocked or leaky. You can try wiping the valve with a clean cloth to see if it helps.

Caution: Turn off the furnace, leave the house, and call a professional if you smell gas; there may be a leak.

Pressure Switch Not Opening [Code 23]

First, unplug and turn off the furnace. Next, look for any obstacles in the system. The pressure switch hose or the flue pipe could both be disconnected or broken.

Secondary Voltage Fuse Open [Code 24]

Inspect the secondary voltage wire for shorts. If you're uncertain about dealing with electrical connection problems, it is best to call for help from professionals.

Open Block Vent, Draft Safeguard, Pressure, or Aux-Limit Switch [Code 31]

The inducer will shut off for 15 minutes before trying again if it is left open for more than five minutes.

You would need to check the following things in this case:

  • inducer voltage issues;
  • suitable vent sizing;
  • malfunctioning inducer motors;
  • blower motor or capacitor issues;
  • pressure switch issues;
  • restricted vents;
  • excessive wind;
  • insufficient combustion air supplies; or
  • obstructed pressure tubing.

Open Flame Roll-Out Or Limit Switch [Code 33]

The furnace code will change to 13 if the switch is left open for more than three minutes. Resetting the flame roll-out switch manually is necessary.

Check for: a broken blower motor or capacitor; a clogged filter or duct system; a loose blower wheel; a broken switch or connection; or an insufficient supply of combustion air.

Final Words

House Heating Unit Repair by Professional Technician

When you notice your Carrier furnace flashing error code 34, check your gas valve, flame sensor, flame burner, and the ground connections of your controls and sensors. 

If you still can't fix the problem, the next best course of action is to call your professional HVAC technician to properly diagnose the problem. 

If you enjoyed this post, check out these other articles on this page: 

Carrier Furnace Solid Orange Light - What Could Be Wrong?

How To Reset A Carrier Furnace

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