Lennox SL22KLV Heat Pump Error 104: High Pressure Detected in Outdoor Unit

When your Lennox SL22KLV heat pump displays error code 104, it indicates a heater relay fault that requires immediate attention to prevent further malfunctioning and guarantee proper system function and energy efficiency.

This fault is often caused by a stuck relay on the thermostat board or an outdoor unit sensor issue, which requires a technician’s visit for proper diagnosis. To troubleshoot, reset the thermostat and check for outdoor unit sensor issues – but if the error persists, it’s likely a more serious problem that needs professional assistance to uncover the root cause.

Understanding Error Code 104

When your Lennox heat pump, specifically the SL22KLV model, displays error code 104, it’s indicating a heater relay fault that requires attention.

This fault is likely caused by a stuck relay, which can stick open or closed, preventing the backup elements from functioning correctly.

If your unit is still under warranty, you may be eligible for relay replacement under warranty coverage.

Don’t try to fix the issue yourself – a technician diagnosis is necessary to resolve the problem.

Professional assistance is required to diagnose and repair the heater relay fault, especially if it’s stuck during heat pump defrost mode.

A technician visit will guarantee the issue is properly resolved, and your outdoor unit high pressure issue is addressed.

Also, Read: Lennox SL22KLV Heat Pump Error Code 103: Outdoor Unit Overcurrent Detected

Causes of Error Code 104

You’re trying to diagnose the root cause of the issue with your Lennox heat pump’s error code 104.

This error code indicates an outdoor unit high pressure issue, which can be caused by several factors.

• Stuck relay on the thermostat board: Prevents backup elements from assisting with heat pump operation or taking over during defrost mode.
• Outdoor unit sensor issue: Requires a technician’s visit for proper diagnosis.
• Faulty control board: Typically requires replacement in most cases.
• Stuck relay: Can be resolved by replacing the relay, which is a common issue in some heat pumps.

These causes can have a profound impact on your heat pump’s operation, and addressing them promptly is crucial to avoid further issues.

Resetting the Thermostat

Resetting the thermostat is a necessary step to troubleshoot the error code 104 on your Lennox heat pump. You’ll want to verify the thermostat is set low enough to engage the heat pump.

Next, turn the power off at the circuit breaker or fuse box. Wait for 30 seconds to allow the system to fully shut down.

Then, turn the power back on and wait for the thermostat to complete its self-test. If the error code persists, it’s likely a more serious problem with your Lennox SL22KLV’s outdoor unit, which may be experiencing high pressure, and you may need expert tips from an HVAC Tech or home repair pros for a successful repair intercession.

Also, Read: Lennox SL22KLV Heat Pump Error Code102: Low Refrigerant Charge Detected

Error Code 104 Resolution

When resolving error code 104 on your Lennox heat pump relay is stuck closed, leading to an outdoor unit high pressure problem.

You’ll likely need a board replacement to fix the issue, which requires professional assistance to diagnose and resolve.

The technician will verify that there’s no call for heat from the thermostat to the outdoor unit and check for outdoor unit sensor issues.

Board Replacement Needed

The stuck relay on your Lennox heat pump model SL22KLV’s outdoor unit control board is likely the culprit behind error code 104, and in most cases, replacement is necessary to resolve the issue.

• The technician will verify that the thermostat is sending a call for the outdoor unit.
• They’ll check the outdoor unit sensor for any issues before replacing the control board.
• In most cases, the control board needs to be replaced to resolve the error code 104 on the Lennox heat pump model SL22KLV.
• This requires professional assistance for proper diagnosis and resolution.

Outdoor Unit Issue

One key aspect of resolving error code 104 on your Lennox heat pump model SL22KLV is addressing the outdoor unit issue.

This high-pressure issue requires professional’s assistance to diagnose and repair. The outdoor unit sensor might be the culprit, and a technician’s visit is necessary to check and potentially replace it.

Don’t waste time shutting off and on the thermostat, as error code 104 persists, indicating a serious error. A professional diagnosis is pivotal to identify the root cause, which may involve board replacement.

To guarantee proper system function, resolving this issue is paramount. A professional technician can fix the outdoor unit high-pressure issue, resolving error code 104 and restoring your system’s function.

Relay Stuck Closed

Faulty relay operation is a common culprit behind error code 104 on your Lennox heat pump model SL22KLV.

A stuck relay prevents the outdoor unit from functioning properly, leading to high pressure and the error code.

• A relay stuck closed keeps the element on unnecessarily, causing the error code.
• If the relay sticks open, the element doesn’t come on, compromising the heat pump’s heating function.
• You may need professional assistance for replacement, especially if the relay is imported from China or Mexico.
• Check your warranty – it may cover the replacement, especially if your heat pump is still under warranty.

Also, Read: Lennox SL22KLV Heat Pump Error Code 101: Loss of Communication Between Outdoor and Indoor Units

Heater Relay Function and Failure

Your Lennox heat pump relies on the heater relay to switch the compressor and condenser fan motor on and off, ensuring efficient heating operation.

This relay function is vital, as it prevents overheating, which can lead to high pressure conditions, triggering the Error Code 104.

In your SL22KLV model, the heater relay failure can cause the outdoor unit to malfunction, resulting in poor air conditioning.

Think of the relay as a valve that regulates the compressor’s blood flow; when it sticks or fails, the entire system suffers.

Understanding the heater relay’s function and potential failure is vital in identifying the root cause of the issue, which is essential for effective troubleshooting and repair.

Repair and Replacement

You’ll need to analyze the relay failure to identify the root cause of the issue.

If the relay is faulty, you’ll need to determine if the entire board is necessary or if the relay can be replaced individually.

Before proceeding with repairs, you should also check if the 3-year-old Trane XL20i 4-ton heat pump’s warranty covers the necessary replacement parts.

Relay Failure Analysis

During Lennox heat pump operation, relay failure can occur due to various reasons, leading to system malfunction.

If you’re experiencing Error Code 104, indicating high pressure in the outdoor unit, relay failure could be the culprit.

• Improper installation: Incorrect wiring or loose connections can cause relay to fail, leading to system malfunction.
• Overheating: High temperatures can cause the relay to fail, triggering the low-pressure shutoff and preventing the HVAC system from operating.
• Electrical surges: Power surges can damage the component, leading to relay failure and system malfunction.
• Wear and tear: Regular servicing and maintenance can help identify worn-out relay components, which can be replaced to prevent relay failure.

Board Replacement Needs

The faulty relay component may necessitate board replacement, which is a critical repair task. You’ll need a professional who specializes in HVAC systems to diagnose the issue accurately. A licensed expert will follow a Multi-Step Expert Quality Process to identify the root cause of the error code 104, which indicates outdoor unit high pressure.

Home improvement experts recommend seeking a reliable HVAC expert for board replacement to guarantee your system operates efficiently and safely. By doing so, you’ll avoid further damage and costly repairs down the line.

Warranty Coverage Check

After identifying the faulty relay component and determining the need for board replacement, it’s vital to investigate warranty coverage for the repair and replacement of the outdoor unit high pressure component.

Since your 3-year-old Lennox SL22KLV heat pump is likely still under warranty, you may be eligible for a free repair.

• Verify warranty status with the HVAC technician to confirm the repair is free of charge.
• Request a warranty check from the HVAC company to confirm coverage and avoid unexpected labor costs.
• Inspect the system to identify any other potential issues contributing to the error code 104.
• Replace the sticking relay in the air handler, a common cause of the error code 104, under warranty.

Also, Read: Lennox XP25 Heat Pump Error Code 471: Dual-Fuel Control System Error

Preventing Future Errors

To keep your Lennox heat pump running smoothly, regular maintenance is key.

You can prevent high pressure issues that trigger error code 104 by inspecting and cleaning the condenser coils regularly.

Proper airflow clearance around the unit, at least 3 feet from obstacles, also reduces the likelihood of high pressure errors.

Verifying the refrigerant charge is at the recommended level helps prevent high pressure issues.

Replacing the air filter every 1-3 months reduces strain on the heat pump system, preventing high pressure errors.

Scheduling Professional Assistance

If you’ve taken steps to prevent error code 104 but still encounter the issue, you’ll need professional assistance to resolve it.

To schedule professional assistance, follow these steps:

• Contact a local HVAC company at 863-216-2923 or online to schedule an appointment.
• Technician expertise is necessary to diagnose and repair or replace the outdoor unit high-pressure switch, which is the likely culprit behind the error code.
• System charge check will be performed using several methods to determine the cause of the issue, and the outdoor unit will be reset by putting it in test mode or resetting low-voltage power.
• Prompt action is essential to prevent further malfunctioning of the heat pump and guarantee proper system function and energy efficiency.

A professional technician’s visit is necessary for proper diagnosis, as attempting to reset the thermostat or outdoor unit without proper diagnosis can cause further damage to the system.

Also, Read: Lennox XP25 Heat Pump Error Code 470: Indoor Humidity Sensor Failure Detected

Frequently Asked Questions

What Causes High Pressure Lockout on Heat Pump?

You’ll find that high pressure lockout on your heat pump is often caused by refrigerant overcharge, blocked air flow, clogged condenser coils, faulty compressor valve, pressure sensor, or improper installation, as well as inadequate maintenance or incorrect refrigerant usage.

What Is Error Code 104 on Thermostat?

When you see error code 104 on your thermostat, it means there’s a high pressure reading, likely due to a faulty sensor, incorrect installation, malfunctioning valve, or pump malfunction, requiring sensor calibration or system check to resolve the outdoor unit issue and prevent a system malfunction or thermostat glitch.

How Do You Reset a Lennox High Pressure Switch?

To reset a high pressure switch, you’ll need to identify the root cause, such as a sensor malfunction or valve problem, then perform switch maintenance, address any electrical issues, and guarantee pressure relief to prevent system failure, before resetting the pressure safety fault detection.

How to Clear Lennox Error Code?

To clear Lennox error codes, you’ll need to identify and fix the underlying outdoor unit issue, which may involve heat pump troubleshooting, fault code diagnosis, and system malfunction detection, ultimately leading to a Lennox technical expert for a heat pump solution.

Conclusion

When your Lennox heat pump model SL22KLV flashes code 104, don’t throw in the towel. This outdoor unit high-pressure error can be resolved. Check the thermostat, inspect the heater relay, and prevent future errors with regular maintenance.

Remember, “an ounce of prevention is worth a pound of cure.” By addressing the issue promptly, you’ll avoid further damage and costly repairs.