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Carrier Furnace Flame Sensor

Carrier Furnace Flame Sensor: What You Need to Know

Is your Carrier furnace flame sensor silently failing? If you have a Carrier furnace, you may have heard of a component called the flame sensor. The flame sensor is a…

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Is your Carrier furnace flame sensor silently failing?

If you have a Carrier furnace, you may have heard of a component called the flame sensor. The flame sensor is a vital part of your heating system that ensures its safety and efficiency. But what exactly is the flame sensor, how does it work, and how do you troubleshoot it? 

In this blog post, we will answer these questions and more.

What is the Flame Sensor?

The flame sensor is a metal rod that is located on the burner assembly inside the furnace. It is usually bent and rests directly in front of the pilot flame. The flame sensor’s job is to detect the presence of a flame and send a signal to the control board. If the flame sensor does not sense a flame, it will shut off the gas valve and prevent the furnace from operating. This prevents gas leaks, explosions, or carbon monoxide poisoning.

How Does the Carrier Furnace Flame Sensor Work?

The flame sensor works by using a phenomenon called flame rectification. Flame rectification is the process of converting an alternating current (AC) into a direct current (DC) by passing it through a flame. The flame acts as a one-way valve that allows the current to flow in one direction only. The control board sends a small AC voltage to the flame sensor, which then passes it through the pilot flame.

The pilot flame converts the AC voltage into a DC voltage and sends it back to the control board. The control board measures the DC voltage and determines if there is a flame or not.

If there is a flame, the control board will keep the gas valve open and allow the furnace to operate. But if there is no flame, the control board will close the gas valve and stop the furnace.

READ: How To Fix The Common Amana Furnace Fault Codes

What Is Carrier Furnace Flame Sensor Location

The Carrier furnace flame sensor is typically located near the burners. To find it, first, turn off the power to the furnace. Then, remove the furnace door to reveal the internal components. The flame sensor is a thin metal rod positioned in front of one of the burners, usually with a single wire connected to it.

It might be on either side of the burners, depending on your Carrier model. For specific instructions or maintenance, refer to your furnace’s manual or consult a professional HVAC technician.

How to Troubleshoot the Flame Sensor?

The flame sensor can sometimes malfunction or fail due to various reasons, such as dirt, corrosion, damage, or wiring issues. A faulty flame sensor can cause your furnace to not ignite, not stay on, or short cycle. To troubleshoot the flame sensor, you should follow these steps:

  • Turn off the power and gas supply to your furnace and wait for a few minutes.
  • Locate the flame sensor on the burner assembly and disconnect its wires from the control board.
  • Use a multimeter to test the continuity of the sensor. Set the multimeter to ohms and touch its probes to the terminals of the sensor.
  • If the multimeter shows zero or very low resistance, then the sensor is closed and working properly.
  • If the multimeter shows infinite or very high resistance, then the sensor is open and faulty.
  • If the sensor is faulty, replace it with a new one that matches your furnace model and specifications.
  • If the Carrier furnace flame sensor is not faulty, check and clean it with a soft cloth or steel wool if it is dirty or corroded.
  • Reconnect the wires and turn on the power and gas supply to your furnace.
  • Observe if your furnace works normally or still has problems.

READ: How to Troubleshoot and Maintain Your Carrier WeatherMaker 9200 Furnace

How to Test a Carrier Furnace Flame Sensor

The Carrier furnace flame sensor is a metal rod that is located on the burner assembly inside the furnace. It is usually bent and rests directly in front of the pilot flame. The flame sensor’s job is to detect the presence of a flame and send a signal to the control board.

If the flame sensor does not sense a flame, it will shut off the gas valve and prevent the furnace from operating. This prevents gas leaks, explosions, or carbon monoxide poisoning.

To test the Carrier furnace flame sensor, you will need a multimeter and some basic tools. Here are the steps to follow:

  • Turn off the power and gas supply to your furnace and wait for a few minutes.
  • Locate the flame sensor on the burner assembly and disconnect its wires from the control board.
  • Use a multimeter to test the continuity of the sensor. Set the multimeter to ohms and touch its probes to the terminals of the sensor.
  • If the multimeter shows zero or very low resistance, then the sensor is closed and working properly.
  • If the multimeter shows infinite or very high resistance, then the sensor is open and faulty.
  • If your Carrier furnace flame sensor is faulty, replace it with a new one that matches your furnace model and specifications.
  • If the sensor is not faulty, check and clean it with a soft cloth or steel wool if it is dirty or corroded.
  • Reconnect the wires and turn on the power and gas supply to your furnace.
  • Observe if your furnace works normally or still has problems.

What Are the Symptoms of a Bad Carrier Furnace Flame Sensor?

A faulty Carrier furnace flame sensor can cause your furnace to not ignite, not stay on, or short cycle. Here are some signs that you have a bad flame sensor in your furnace:

  • The tip of the flame sensor has visible rust, dust, or soot.
  • The porcelain base of the flame sensor is chipped, cracked, or completely broken.
  • The furnace lights but then shuts down after a few seconds (short cycles).
  • The furnace shuts down several seconds after lighting up.
  • The furnace turns on and off very quickly (after 2-30 seconds).

If you notice any of these symptoms, you should test your flame sensor as described above and fix it as soon as possible.

How to Prevent Flame Sensor Problems?

The best way to prevent Carrier furnace flame sensor problems is to maintain your furnace regularly and properly. Here are some tips on how to do that:

  • Change your air filter every month or as recommended by your manufacturer
  • Clean your furnace components such as burners, blower, heat exchanger, etc., at least once a year
  • Inspect your venting system and make sure it is clear of any obstruction or damage
  • Check your thermostat and make sure it is working correctly and calibrated
  • Schedule a professional tune-up for your furnace at least once a year

By following these tips, you can keep your furnace in good shape and avoid many common problems and codes.

READ: Common HVAC Sequencer Problems and How to Fix Them

Conclusion

The Carrier furnace flame sensor is an important part of your Carrier furnace that ensures its safety and efficiency. It works by detecting the presence of a flame and sending a signal to the control board. If it malfunctions or fails, it can cause your furnace to not work properly or at all. To fix it, you need to test, clean, or replace it as needed. To prevent it from failing, you need to maintain your furnace regularly and properly.

We hope you found this blog post useful and informative.

I'm an HVAC enthusiast and a passionate writer dedicated to sharing valuable insights and practical tips about heating, cooling, ventilation, and air conditioning systems.

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Hi there, I'm Robert Brooks

Hi there, I'm Robert Brooks

I’m so glad you are here! Welcome to my website, where I’ll share easiest HVAC troubleshooting tips, buyers guides, and everything about HVAC cooling and heating system. Learn more about me.

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