RV Furnace Sail Switch Location Guide: Locating, Diagnosing, and Maintaining for Optimum Heating

For RV owners, a functioning furnace is essential for comfort during chilly nights. One critical but often overlooked component is the sail switch. This article explores where to find the sail switch in your RV furnace, why it matters, and tips for troubleshooting common issues. This guide is tailored for American RV users and enthusiasts seeking reliable, in-depth information about the sail switch’s location and maintenance.

Key Points At A Glance

Topic	Summary
What Is a Sail Switch?	Safety device ensuring adequate airflow before ignition
Common Furnace Brands	Suburban, Dometic/Atwood, Hydro Flame, and others
Typical Location	Near blower assembly, in the air flow path
Symptoms of Fault	Blower runs, furnace will not ignite
DIY Access	Requires panel removal, moderate skill level

What Is A Sail Switch In An RV Furnace?

The sail switch is a safety device installed inside RV propane furnaces. Its purpose is simple but vital: it detects whether the blower fan is moving enough air before allowing the furnace burner to ignite. This mechanism ensures the combustion chamber never ignites unless proper airflow is present, preventing gas buildup and potential hazards.

Why The Sail Switch Is Crucial For Safety And Functionality

If the sail switch fails or is blocked, it prevents the furnace from igniting to avoid unsafe conditions. That’s why, when the blower comes on but you hear no burner ignition, a faulty or obstructed sail switch is one of the first suspects. Ignoring this device can risk both your RV’s heating and your safety.

Common RV Furnace Brands And Their Configurations

Most American RVs feature forced-air furnaces by key brands such as Suburban, Dometic/Atwood, and Hydro Flame. While internal layouts vary, these brands typically house the sail switch in a similar area. Knowing the brand and model of your furnace will help you locate and access the sail switch quickly.

General Location Of The RV Furnace Sail Switch

The sail switch is typically mounted near the blower wheel and in the discharge air path, upstream of the heat exchanger. Access often involves removing the outer access panel, then locating the switch within the main air duct inside the furnace case. Its small paddle or “sail” sits in the air stream, pressed by moving air from the blower.

Step-By-Step Instructions: Finding The Sail Switch In Your RV Furnace

1. Power Down And Ensure Safety

Always disconnect all power and turn off propane before working on the furnace. Wait until the furnace cools to avoid burns.

2. Remove Furnace Access Door Or Panel

Locate the outdoor access panel, usually found along your RV’s exterior or inside a service bay. Remove screws or latches and gently detach the panel.

3. Identify The Blower And Air Chamber

The blower assembly is typically on one side of the furnace’s casing. Look for a metal duct through which air is pushed into the RV.

4. Spot The Sail Switch

Inside the flow path, look for a rectangular component with a flat paddle resembling a small sheet or lever. Wiring will connect it to the furnace’s control circuit. The paddle is positioned directly in the airflow, so it moves freely when the fan operates.

5. Accessing The Sail Switch

On some models, further disassembly of internal panels or ductwork may be required. Refer to the owner’s manual or consult diagrams specific to your furnace model for detailed guidance.

Brand-Specific Sail Switch Location Tips

Suburban Furnaces

For most Suburban models, like the SF-30F, SF-35F, and SF-42F, the sail switch is located near the main blower wheel. After removing the exterior access cover, the switch is typically mounted on the dividing wall between the cold air return and the heating chamber. Look for two wires connected to the switch.

Dometic/Atwood Furnaces

On many Dometic/Atwood models, such as the AFMD and AFLC series, the sail switch can be found just past the blower, in the return air pathway. Access may involve detaching a small internal cover. The switch usually has a metal bracket and is secured with screws.

Hydro Flame Furnaces

Hydro Flame (now under Dometic) uses a similar layout. The sail switch is usually found alongside the limit switch near the air output side. It’s typically attached to a support bracket in the air duct’s path, reachable after exterior panel removal.

Visual Guide: Sail Switch Appearance And Mounting

The sail switch is easily identified by its thin, flat, metal or plastic “paddle.” This paddle is attached to a small micro switch. When airflow is adequate, the paddle lifts or moves, closing the switch contacts and allowing the furnace to ignite. Lack of airflow (or a blocked paddle) keeps the circuit open, disabling ignition for safety.

Feature	Description
Body	Small rectangular or square casing, typically metal or plastic
Paddle (“Sail”)	Flat lever, positioned in the air stream to sense movement
Wiring	Usually two wires, forming part of the control circuit
Mounting	Secured with screws; bracket may be used

Common Symptoms Of A Faulty Or Blocked Sail Switch

• Blower runs, but burner never ignites
• Clicking or “whooshing” sounds without heat
• No propane smell or flame at the exhaust
• Error lights or furnace lockout conditions
• Furnace works intermittently, especially if RV is not level

These symptoms often indicate a sail switch problem or overall airflow obstruction, such as dirty filters or debris in the blower compartment.

Why The Sail Switch Might Fail Or Malfunction

• Dust or debris obstructing the paddle, preventing it from moving freely
• Mechanical wear or corrosion of the switch contacts
• Electrical connection issues in the wiring
• Insufficient airflow due to a failing blower or blocked vents

Any of these issues can cause the sail switch to remain open, breaking the ignition circuit and stopping your furnace from firing.

Essential Tools For Locating And Servicing The Sail Switch

• Phillips and flathead screwdrivers (for access panels and switch mounting)
• Needle-nose pliers (for wire connections)
• Multimeter (for electrical continuity tests)
• Owner’s manual or service diagrams

Always ensure safe and correct procedures when accessing electrical or propane components. Consult a professional if you are unsure.

Simple DIY Troubleshooting: Testing The Sail Switch

Conducting A Continuity Test

Using a multimeter, check for continuity between the terminals with the blower operating. No continuity generally signals a failed or blocked switch. Be sure to isolate power before handling any wiring.

• Remove switch wires
• Set multimeter to continuity check mode
• Test across terminals while fan is running
• Movement or closure of contacts should allow continuity

Maintenance And Cleaning Tips To Prevent Sail Switch Issues

• Regularly inspect and clean the blower compartment to prevent dust buildup
• Periodically check the sail switch paddle for free movement
• Ensure all vent and return air pathways remain unobstructed
• Lubricate moving parts sparingly, if recommended by your manufacturer

Proactive cleaning and maintenance can extend the lifespan of your RV furnace sail switch and help prevent inconvenient heating failures on your journeys.

When To Replace The Sail Switch

If cleaning and testing fail to resolve furnace ignition issues, replacement is often the best solution. Sail switches are affordable parts and are available both through RV supply stores and online retailers. Always purchase a model compatible with your specific furnace.

Replacement Procedure Overview

• Disconnect power and propane
• Remove access panels and locate the switch
• Carefully disconnect wires from the old switch
• Remove screws or brackets to release the switch
• Install the new switch, reattach wiring, and secure all panels

Test the furnace after reassembly to verify successful repair and proper heating function.

Frequently Asked Questions About RV Furnace Sail Switch Location

Is The Sail Switch Accessible Without Removing The Furnace From The RV?

In many models, the sail switch can be accessed by removing only the exterior access panel. Certain compact furnaces may require additional disassembly or, rarely, removal from the coach if access is extremely limited.

How Can I Tell If My RV Furnace Issue Is The Sail Switch?

The most common sign is the blower runs but the burner won’t ignite. Other electrical or airflow issues can cause similar symptoms. Testing with a multimeter confirms if the sail switch is failing to close with proper airflow.

Can The Furnace Run Without The Sail Switch?

No. By design, the sail switch is a critical safety interlock. Bypassing or overriding it is unsafe and may void warranties and insurance coverage.

Are Sail Switches The Same For All Furnaces?

No. While the concept is the same, sail switches are model-specific in size and electrical characteristics. Use only the correct part number as listed in your furnace documentation.

Should I Attempt A Sail Switch Repair Myself?

If you are familiar with electrical and propane appliance servicing, it can be a manageable DIY task. If uncertain, consult a certified RV technician to ensure your system remains safe and reliable.

Tips For Preventing Future Sail Switch Problems

• Perform annual furnace maintenance, especially before the heating season
• Clean all vents, ducts, and blower interiors regularly
• Store your RV with access doors sealed to keep out dust and pests
• Check the operation of the furnace at least monthly when in use

Consistent care of your RV furnace and sail switch can keep your RV cozy, safe, and efficient for years to come.

Helpful Resources And Further Reading

• RV Forum Online: Heating and Furnace FAQs
• RVtechLibrary: RV Furnace Manuals
• Dometic Support: Furnace Manuals and Diagrams
• Suburban RV Parts: Technical Documents

Summary Table: Locating The RV Furnace Sail Switch By Brand

Furnace Brand	Sail Switch Relative Location	Access Method
Suburban	Near blower, between air return and burner chamber	Remove exterior access panel
Dometic/Atwood	Inside air return path, near blower output	Remove panel, possibly inner cover
Hydro Flame	On bracket by blower or limit switch	Remove panel, limited disassembly

Key Takeaway For RV Owners

The sail switch is a small yet vital furnace safety component located inside the blower airflow path. Understanding its location by furnace brand, as well as proper troubleshooting and maintenance, ensures warmth and safety wherever your RV travels take you.