Coleman Furnace Light Codes Guide for Troubleshooting and Maintenance

Coleman furnaces are widely used for reliable home heating. When a malfunction occurs, the furnace’s diagnostic system signals issues via light codes, making it easier to identify problems swiftly. Understanding these Coleman furnace light codes is essential for efficient troubleshooting and maintenance. This guide provides a clear explanation of common light codes, their meanings, and recommended actions to restore your heating system effectively.

Light Code Pattern	Common Cause	Recommended Action
1 Flash	Pressure switch failure or airflow issues	Check venting and air filters, inspect pressure switch
2 Flashes	Ignition failure	Inspect ignitor and flame sensor, clean or replace parts
3 Flashes	Flame sensing failure	Clean flame sensor, verify gas supply
4 Flashes	Pressure switch stuck closed or limit switch problem	Check pressure switch and limit switch, replace if needed
5 Flashes	Open high limit or rollout switch	Inspect for blockages or overheating, service or replace switches

How Coleman Furnace Light Codes Work

Coleman furnaces use an LED light on the control board to indicate operational status. When the furnace detects an error, it flashes this light in a specific sequence. Each sequence, counted as a number of flashes followed by a pause, corresponds to a certain fault. This system provides a quick, straightforward way for homeowners and technicians to diagnose issues without specialized equipment.

Common Coleman Furnace Light Codes and Their Meanings

1 Flash: Pressure Switch or Airflow Issues

A single flash typically points to a pressure switch failure or airflow blockage. The pressure switch ensures the furnace exhaust system is operating safely. Restricted airflow from dirty air filters or clogged vents can cause this fault.

• Check and replace dirty air filters regularly.
• Inspect intake and exhaust vents for obstructions or damage.
• Test the pressure switch by unhooking the vacuum and measuring switch continuity with a multimeter.

2 Flashes: Ignition Failure

Two flashes often indicate the furnace failed to ignite the gas burner after multiple attempts. Common reasons include faulty ignitors, poor gas supply, or burner issues.

• Examine the ignitor for cracks or wear and replace if necessary.
• Ensure the gas valve is open and the supply is uninterrupted.
• Inspect burner tubes for dirt or rust obstructing gas flow.

3 Flashes: Flame Sensing Failure

This code signals the flame sensor did not detect a flame once the burner was lit. A flame sensor covered in residue can misread safety signals and shut down the system.

• Carefully clean the flame sensor rod with fine steel wool or emery cloth.
• Check gas pressure to verify steady flame.
• Replace the flame sensor if cleaning does not resolve the issue.

4 Flashes: Pressure Switch Stuck Closed or Limit Switch Faults

Four flashes usually mean the pressure switch remains closed when it should open, or there is a limit switch malfunction. This can cause the furnace to shut down due to safety concerns.

• Test the pressure switch by verifying its opening when the inducer motor runs.
• Inspect the limit switch for signs of overheating or damage and replace if needed.

5 Flashes: Open High Limit or Rollout Switch

Five flashes indicate an open high limit or rollout switch, which stops the furnace if it detects dangerously high temperatures or flame rollout.

• Check for blocked airflow or dirty burners causing overheating.
• Examine the rollout switch and high limit switch for damage or false triggers.
• Ensure proper clearance around the furnace for ventilation.

Troubleshooting and Safety Tips for Coleman Furnace Lights

Regular maintenance and proper safety precautions are crucial when addressing furnace issues. Always disconnect power before inspecting electrical components to avoid shocks.

• Keep air filters clean and replace them every 1-3 months to maintain airflow.
• Ensure proper vent pipe installation and no blockages in exhaust or intake paths.
• If in doubt, contact a certified HVAC technician instead of attempting complex repairs.
• Use the furnace manual to verify specific light codes, as models can vary slightly.

How to Reset Coleman Furnace After a Fault

Many Coleman furnaces allow reset by switching the power off and on:

1. Turn off the thermostat and furnace power switch.
2. Wait at least 30 seconds to one minute.
3. Turn the furnace power back on.
4. Set the thermostat back to the desired temperature.

If the furnace immediately returns to flashing fault codes, further diagnosis is required.

When to Call a Professional HVAC Technician

Some furnace issues require expert knowledge and tools. A professional technician should be called if:

• You cannot resolve persistent error codes after basic troubleshooting.
• The furnace is making unusual noises, such as banging or rattling.
• You suspect gas leaks or smell gas near the furnace.
• Electrical components or control boards need inspection or replacement.
• Safety switches repeatedly trip, indicating complex failures.

Summary Table of Coleman Furnace Light Codes and Actions

Light Code	Error Description	Primary Cause	Troubleshooting Steps
1 Flash	Pressure switch or airflow problem	Blocked vent, dirty air filter	Check/clean vents and filters, test pressure switch
2 Flashes	Ignition failure	Faulty ignitor, gas valve issue	Inspect ignitor, verify gas supply, clean burners
3 Flashes	Flame sensing failure	Dirty flame sensor	Clean or replace flame sensor, check flame stability
4 Flashes	Pressure switch stuck or limit switch problem	Faulty switches	Test pressure and limit switches, replace if necessary
5 Flashes	Open high limit or rollout switch	Overheating, blocked airflow	Inspect switches, ensure proper airflow, clean burners