Clearing Error Code 223 on Your Lennox® Furnace

Getting cold because you’re noticing error code 223 from your Lennox® furnace?

This is telling you your furnace’s low pressure switch is open. Due to the issue, your system will not run for your safety.

Turn to the Experts at San Antonio Air Service Experts to handle fixing this furnace error. Our NATE-certified technicians are among the elite in the industry when it comes to recognizing and repairing furnace issues.

Your satisfaction is important to our team. That’s why we back our furnace repair work in San Antonio with a 100% Satisfaction Guarantee* for a year.

How a Low Pressure Switch Works

Pressure switches are a necessary part of the heating system.

Here’s how your furnace works after the thermostat starts to call for heat:

  • Your furnace’s control board begins the draft inducer blower motor. This exhausts combustion gases from the heat exchanger and pulls in new gas and air so the burners can fire.
  • When the pressure switch senses that enough air is being pulled into the burners, it closes and tells the control board to ignite the furnace.
  • Your furnace ignites and heats your space.

A two-stage furnace has several pressure switches, which help it to run at different speeds—and use energy more efficiently.

What Happens When a Low Pressure Switch Fails

The low pressure switch may be open for several reasons.

There could be a:

  • Obstructed vent
  • Plugged condensate drain
  • Cracked hose

There could also be trouble with the switch itself, the inducer or the circuit board.

Your furnace will tell you there’s an issue with a red flash from its indicator light, which it uses to feature error codes. It has this red light to flash code, like Morse code.

You might observe fast flashes or an alternating slow flash as it reiterates a fault code.

Estimated Repair Cost for Furnace Error Code 223

The cost to fix your furnace depends on what’s wrong with it and how long it takes to remedy it.

Here are average replacement costs for several components that could be affected:

  • Pressure switch—$40 to $350
  • Inducer—$600 to $1,500
  • Circuit board—$200 to $600

Call the Experts at San Antonio Air Service Experts

When you need furnace service, you can call on the professionals at San Antonio Air Service Experts to take care of the fault code and get your heat moving again.

Call us at 210-570-9705 or schedule an appointment online today.


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At Service Experts, our top priority is always the health and safety of our customers and team. We are following all COVID-19 (Coronavirus) public safety guidelines and adjusting our business practices as needed to ensure customer and employee wellbeing. As a precautionary measure, anyone working on behalf of Service Experts – including our technicians – is being asked to stay home for the recommended 14 day quarantine period if they are returning from out-of-country, have been exposed to a presumptive or confirmed case, or are feeling unwell. We are providing our technicians and other field employees with additional health and safety guidance to assist in keeping our customers and employees safe. Please be prepared to answer brief health and safety questions with our representative. We will continue to monitor the situation and will adjust our business practices as required. We recognize that this may be a particularly stressful time and want you to know that, we are committed to serving you and making your experience as easy as possible.