Lennox SL22KLV Heat Pump Error Code 129: Communication Failure Between Thermostat and Unit

Your Lennox heat pump model SL22KLV is displaying error code 129, indicating a refrigerant flow issue and a communication error between the thermostat and outdoor unit.

You’ll need to inspect the wiring and connections to verify they’re secure and functioning properly, and check the outdoor unit connection and thermostat connection for signs of damage, corrosion, or wear. If you’re still unsure, continue to explore the troubleshooting steps to get your heat pump up and running smoothly again.

Understanding Error Code 129

When your Lennox heat pump displays error code 129, you’re likely dealing with a refrigerant flow issue.

This error is often accompanied by a communication error between the thermostat and the outdoor unit. The communication error can be caused by a faulty wire connection, a malfunctioning thermostat, or a problem with the outdoor unit itself.

To guarantee a solution to the error code 129, you must pinpoint the root cause of the issue. You’ll need to inspect the wiring and connections to verify they’re secure and functioning properly.

Once you’ve identified the problem, you can take the necessary steps to rectify the issue and get your heat pump up and running smoothly.

Also, Read: Lennox SL22KLV Heat Pump Error Code 128: Indoor Fan Motor Failure Detected

Troubleshooting Steps for Communication Errors

To address the communication error between the thermostat and the outdoor unit, inspect the wiring and connections. Certify that all wires are securely connected to the outdoor unit and the thermostat. Check for signs of damage, corrosion, or wear.

If you’ve checked the wiring and connections, but the error persists, consult your user manual for further troubleshooting steps or contact a licensed HVAC technician for assistance.

Solving Error Code 411: Low-Pressure Switch Malfunction

How does a Lennox heat pump respond when its low-pressure switch malfunctions?

When the low-pressure switch opens incorrectly five times or more during one heating or cooling cycle, error code 411 appears.

• The error count increases every time the low-pressure switch opens, and the outdoor unit shuts down once it reaches five strikes.
• A technician will check the system using several methods to determine the cause of the issue, such as checking refrigerant levels or inspecting the system components for a float switch malfunction.
• The technician can reset the outdoor unit by putting it in test mode or resetting low-voltage power, and the error code should automatically clear once the issue is fixed.
• The technician may need to perform additional tests, such as checking the condenser coil for blockages or inspecting the refrigerant lines for leaks, to identify the root cause of the low-pressure switch malfunction, clearing the Error code 411.

Also, Read: Lennox SL22KLV Heat Pump Error Code126: Relay Failure Detected in Control Circuit

Fixing Error Code 225: High-Pressure Switch Issue

When you encounter error code 225 on your Lennox heat pump, you’ll need to identify the root cause and troubleshoot the issue.

You’ll focus on the high-pressure switch, a critical safety component, and inspect the vent and combustion air inducer for blockages that may be triggering the error.

Identifying Causes

As you diagnose the high-pressure switch issue, vital to understand that error code 225 specifically relates to the furnace’s safety component, which releases high pressure when airflow is obstructed.

This component is critical to preventing damage to your furnace.

To identify the cause, you’ll need to:

• Perform a furnace inspection to identify any signs of blockage or restriction.
• Conduct pressure measurement to determine if the pressure is within the recommended range.
• Analyze airflow to identify any obstructions or restrictions.
• Inspect the vent and combustion air inducer to locate the blockage causing the high-pressure switch malfunction.

Troubleshooting Steps

To fix error code 225, you need to take a systematic approach to identify and address the underlying cause of the high-pressure switch malfunction. The technician will watch the high-pressure switch to determine how it functions and measure the pressure while it attempts to close during a heating cycle. They will also check the vent and combustion air inducer to locate the blockage that is causing the high-pressure switch to malfunction.

Also, Read: Lennox SL22KLV Heat Pump Error Code127: Outdoor Fan Motor Failure Detected

Resolving Error Code 31: Thermostat Communication Failure

If your Lennox heat pump displays Code 31, it’s likely that the thermostat is failing to communicate with the outdoor unit.

This communication breakdown can be caused by Thermostat Issues, resulting in a Signal Failure.

To resolve this issue, follow these steps:

• Check the thermostat wiring for any signs of damage or corrosion.
• Verify the thermostat’s battery level, ensuring it has sufficient power to transmit signals.
• Restart the thermostat and outdoor unit to re-establish communication.
• Inspect the outdoor unit’s communication module for any signs.

Anytime, Anywhere Troubleshooting With Lennoxpros

You can access error code troubleshooting anytime, anywhere with LennoxPros, eliminating the need for internet searches and reducing time spent on hold.

With LennoxPros, you can instantly access troubleshooting steps, expediting service and simplifying your workflow.

The Error Code Lookup feature is available free, with no registration or sign-in required, and can be accessed on any device.

As a technician, you can use LennoxPros in the office or in the field, and get started right away without additional training.

Lennox Pros offers Service Simplified, giving you the freedom to troubleshoot and resolve issues efficiently, anywhere, anytime.

Also, Read: Lennox SL22KLV Heat Pump Error Code 125: Control Board Malfunction Detected

Accessibility Features of LennoxPros

LennoxPros’ user-friendly design guarantees that the Error Code Lookup feature and other technical tools are easily accessible.

You can access the feature on LennoxPros App or website, without registration or sign-in.

• Language preference: You can select English or Español as your preferred language, and the site remembers your location and language preference.
• Location selection: You can select your location from the United States, Canada (Outside of Qubec), or Quebec, and cookies may be used to remember your answer.
• Registration: You can sign in with your credentials or register in 3 easy steps to access pricing and ordering.
• User navigation: The website optimization confirms easy navigation, making it convenient for you to find what you need.

Account Management and Exclusive Resources

The account management system streamlines your experience by providing access to exclusive resources, allowing you to efficiently manage your account and stay informed about Lennox heat pump products.

Through a user-friendly interface, you can access a personalized dashboard that centralizes all your account information, product details, and customer support resources.

This enables you to troubleshoot issues like error code 129, or find answers to common questions, quickly and easily.

With dedicated customer support just a click away, you can focus on what matters most – getting your Lennox heat pump up and running smoothly.

Location and Language Preferences for Optimal Experience

Customizing your experience begins with selecting your location and language preferences.

This guarantees you get the most relevant information for your.

You can choose from:**

• United States for a tailored experience in the US.
• Canada (Outside of Quebec) for a specific Canadian experience outside of Quebec.
• Quebec for a unique Quebec-specific experience.
• Language Preferences: Select English or Español to access the application form in your preferred language.

Also, Read: Lennox SL22KLV Heat Pump Error Code 124: Insufficient Heating Due to Reversing Valve Issue

Resources and Tools for HVAC Professionals

You have instant access to troubleshooting steps and resources through the Error Code Lookup tool, available anywhere, without registration or sign-in.

This free tool provides you with expedited error code resolution, reducing time spent on hold, and expediting service for your customers.

With the Error Code Lookup, you can quickly resolve issues like the Lennox Heat Pump Model Num: SL22KLV, Error code – 129, Communication Error (Between Thermostat and Unit).

Error Code Lookup

LennoxPros.com’s Technical Tools section streamlines your service calls by providing a reliable Error Code Lookup resource.

This error code reference eliminates the need for internet searches and expedites service. You can access it without registration or sign-in, and it’s available free to any technician who services Lennox products.

The benefits of using LennoxPros.com’s Error Code Lookup are:

• Accessible anywhere: Use it in the office or in the field, on a desktop, mobile, or tablet device.
• No registration required: Existing members can sign in, while non-members can register in 3 easy steps.
• Multilingual support: The application form language can be selected as English or Español.
• Personalized experience: The site remembers your location and language preference, with cookies used to remember your answer.

Instant Troubleshooting Steps

Error Code Lookup accelerates your service workflow, and now it’s time to streamline your troubleshooting process.

With instant access to error codes, you can quickly identify the issue and get to work on a Quick Fix.

For a Rapid Solution, follow these Instant Troubleshooting Steps:

Check the thermostat and unit connections, ensuring they’re secure and not damaged.

Verify that the thermostat is properly configured and paired with the heat pump.

If issues persist, reset the thermostat and heat pump, then re-pair them.

Accessible Anywhere

As an HVAC professional, your work takes you to various locations, and you need resources that can keep up.

That’s why LennoxPros.com and the LennoxPros App are designed to provide you with remote access to the tools you need, whenever and wherever you need them.

With LennoxPros, you get:

• On demand support: Access error code lookup, pricing, and ordering instantly, without registration or sign-in.
• Mobile convenience: Use the LennoxPros App to troubleshoot on-the-go, and the website will remember your location and language preferences.
• Instant troubleshooting: Error Code Lookup provides immediate access to steps, reducing time spent on internet searches.
• Exclusive benefits: Register or sign in to access promotions, pricing, and ordering, all in one place.

With LennoxPros, you can focus on what matters most – providing exceptional service to your customers.

Also, Read: Lennox SL22KLV Heat Pump Error Code 123: Insufficient Cooling Due to Evaporator Issues

Error Code Lookup: A Valuable Resource for Technicians

You can instantly access a valuable resource that eliminates the need for internet searches and reduces time on hold, expediting service: Error Code Lookup.

This tool is available under Technical Tools on LennoxPros.com, with no registration or sign-in required. As a technician, you can use it free of charge, whether in the office or in the field, on your desktop, mobile, or tablet.

Error Code Lookup provides troubleshooting steps that are instantly available, saving your customers’ time by expediting their service call.

When you need Technical Support, this resource is at your fingertips, allowing you to quickly identify and resolve the issue, getting your customers back up and running in no time.

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In Haines City and surrounding areas, Air Commanders Heating & Air Conditioning Co. is the go-to company for all HVAC needs.

As a local resident, you can rely on their skilled technicians for a complete range of HVAC services to servicing and inspecting existing systems.

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• Expert Technicians: Their technicians provide skilled services, from installing up-to-date systems to troubleshooting issues like the Lennox Heat Pump Model Num: SL22KLV error code 129.
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Also, Read: Lennox SL22KLV Heat Pump Error Code 122: High Pressure Switch Open Detected

Frequently Asked Questions

What Is the Code E229 on a Lennox Furnace?

You’re probably not thrilled to see code E229 on your Lennox furnace, indicating a furnace malfunction, which can lead to heating issues and system failure. Luckily, this error code typically points to a high-pressure switch issue, which a technician can fix with relative ease.

How to Reset Lennox Communicating System?

To reset the Lennox communicating system, you’ll need to perform a System Restart, followed by a Communication Reset to re-establish the connection. Finally, complete a Thermostat Refresh to guarantee seamless communication between the thermostat and unit.

What Is the Communication Error on a Thermostat?

You’re experiencing a communication error on your thermostat, where signal strength is weak, and wireless interference is high, causing incompatible devices to malfunction, resulting in errors, and system failures.

How to Clear Lennox Error Code?

When clearing an error code, you’ll need to consult error diagnosis tools, system troubleshooting guides, and directories to identify the issue, then methodically troubleshoot the system, checking circuit breakers, wiring, and connections to resolve the communication fault.

Conclusion

Smoothly silencing the Lennox heat pump’s startling error code 129, you’ve successfully diagnosed the communication breakdown between thermostat and unit. By following these troubleshooting tales, you’ve tackled pesky pressure switch problems, thermostat tangles, and language barriers.

Now, armed with this valuable knowledge, you’re ready to conquer any HVAC hurdle that comes your way.