Where to Find the High Limit Switch on a Goodman Furnace

Locating the high limit switch on a Goodman furnace is essential for troubleshooting and maintenance. This safety device protects the furnace from overheating by shutting off the burner if temperatures rise above safe limits. Understanding its location can help homeowners and HVAC technicians quickly address furnace issues and maintain system efficiency without unnecessary service delays.

Component	Description	Typical Location on Goodman Furnace
High Limit Switch	Temperature sensor that cuts power to the burner if overheating occurs	Mounted on or near the furnace’s heat exchanger or blower compartment
Heat Exchanger	Transfers heat to the air without combustion gases mixing with indoor air	Central furnace component, usually a metal box or coil system
Blower Compartment	Houses the fan that circulates warm air through your home	Typically located below or adjacent to the heat exchanger

What Is the High Limit Switch and Why Is It Important?

The high limit switch is a critical safety device inside a Goodman furnace. It monitors the temperature inside the heat exchanger area and prevents the furnace from overheating, which can damage components or create fire hazards. When the temperature exceeds the preset limit, the switch interrupts the electrical circuit to the gas valve or burner, causing the flame to shut off.

Without this switch functioning properly, the furnace could continue heating despite dangerous conditions, resulting in potential system failure or safety risks.

Typical High Limit Switch Location on Goodman Furnaces

Goodman furnaces vary by model, but the high limit switch is generally located on or near the heat exchanger or within the blower compartment. Common placement areas include:

• On the furnace’s heat exchanger housing: Attached to the metal surface to monitor temperature accurately.
• Near the burners: Positioned to detect excessive flame or heat buildup.
• Inside the blower compartment: This area experiences airflow from the heated air passing through, making it an ideal place for temperature monitoring.

This positioning helps ensure the switch detects dangerous temperature rises quickly and reliably.

How to Identify the High Limit Switch on Your Goodman Furnace

The high limit switch usually looks like a small round or rectangular component with a plastic or metal casing and two or three electrical wires attached. To identify it:

• Turn off power to the furnace for safety.
• Locate the blower compartment or remove the access panel to expose the heat exchanger area.
• Look for a sensor mounted on the furnace’s metal housing with wires running to the furnace control board or gas valve.
• The switch is often labeled in the user manual, wiring diagram decal inside the furnace panel, or stamped on the part itself.

Recognizing the high limit switch is easier by referring to your furnace model’s specific wiring diagram.

Common Symptoms of a Faulty High Limit Switch

A malfunctioning high limit switch can cause several operational issues, including:

• Furnace shutting off prematurely after short heating cycles.
• No heat output despite the blower running.
• Furnace blower running continuously without heating.
• Repeated furnace lockouts or error codes related to overheating.

If these symptoms occur, the high limit switch may be failing or tripped, indicating overheating or airflow problems that need correction.

Testing the High Limit Switch on a Goodman Furnace

To test the high limit switch accurately, follow these steps:

1. Turn off power and gas supply to the furnace for safety.
2. Access the high limit switch location by removing the furnace panel.
3. Disconnect wires from the switch terminals.
4. Use a multimeter set to the continuity or resistance setting.
5. Test across the terminals; a functioning switch shows continuity (close circuit) at room temperature.
6. If there is no continuity, the switch is open and likely faulty.

This simple test helps determine if replacement is necessary before proceeding with further diagnostics.

Replacing the High Limit Switch on a Goodman Furnace

If the high limit switch tests faulty, replacement is straightforward:

• Order the exact OEM switch compatible with your Goodman model.
• Power off the furnace and gas supply.
• Remove the electrical connectors and mounting screws holding the switch.
• Install the new switch in the same position.
• Reconnect wires and restore power.
• Test furnace operation to confirm the issue is resolved.

Always ensure the replacement switch matches temperature ratings specified by Goodman for your model.

Preventing High Limit Switch Tripping Through Proper Maintenance

The high limit switch often trips due to furnace overheating caused by poor airflow or system problems. Maintaining your furnace can help avoid this, including:

• Regularly changing or cleaning air filters to allow proper airflow.
• Ensuring vents and registers are open and unobstructed.
• Cleaning blower fans and motor to improve efficiency.
• Inspecting and cleaning heat exchangers to prevent heat buildup.
• Scheduling annual professional furnace inspections and tune-ups.

Consistent maintenance protects the high limit switch’s function and prolongs furnace lifespan.

Helpful Tips for Locating and Accessing the High Limit Switch

Many Goodman furnaces have accessible panels designed for routine maintenance. Use these tips to locate the high limit switch quickly:

• Consult the furnace owner’s manual or installation guide; most include component diagrams.
• Look for the blower access panel; the switch is often behind or adjacent to this area.
• Use a flashlight to spot mounted devices with wires attached near the heat exchanger pipes.
• Label wires before disconnecting to avoid confusion during reassembly.

Proper documentation and careful handling reduce troubleshooting time and prevent errors.