Suburban 233383 Sail Switch – Furnace Low Air Flow Switch (Replaces 233070, SH-35 / P-40S)

Product Overview

The Suburban 233383 Sail Switch (formerly part 233070) is a low air flow safety switch designed for select Suburban SH and P series RV furnaces. This switch ensures the blower is moving sufficient air before allowing ignition, helping protect your furnace from unsafe operation.

If your furnace blower runs but the burner will not ignite, the sail switch is one of the most common causes. Replacing a faulty sail switch can quickly restore proper furnace function and reliable heat.

Key Features

• Replaces Suburban part 233070 (updated part number 233383)
• Designed for Suburban SH-35 and P-40S series furnaces
• Low air flow safety switch (sail switch)
• Ensures proper airflow before ignition
• Helps prevent ignition failure and unsafe operation
• Common fix for “blower runs but no heat” issues
• Direct OEM replacement for proper fit and function
• Single switch design
• Durable construction for long service life

Specifications

• Part Number: 233383
• Replaces: 233070
• Product Type: Sail switch / low air flow switch
• Configuration: Single
• Function: Airflow verification before ignition
• Application: Suburban SH and P series furnaces

Compatible Furnace Models

Suburban SH Series

• SH-35
• SH-35F

Suburban P Series

• P-40S

Important Compatibility Note

• Designed specifically for SH-35, SH-35F, and P-40S models
• Verify your furnace model before ordering
• Not compatible with SF or NT series furnaces

When Should You Replace the Sail Switch?

You may need the 233383 sail switch if your furnace:

• Blower fan runs but the burner will not ignite
• Has no spark or ignition after startup
• Cycles without producing heat
• Works intermittently
• Has dust or debris restricting airflow

The sail switch is one of the most commonly replaced furnace components.

Why This Part Matters

• Ensures safe furnace operation by verifying airflow
• Prevents ignition when airflow is insufficient
• Restores proper furnace startup sequence
• Simple and cost-effective repair for common furnace issues

FAQ

What part does this replace?
This replaces Suburban part 233070.

What does a sail switch do?
It verifies that the blower is moving air before allowing ignition.

Is this a common failure part?
Yes, it is one of the most common causes of “blower runs but no heat”.

Will this fit SF or NT furnaces?
No, this switch is designed specifically for SH-35 and P-40S series furnaces.

Is installation difficult?
Installation is typically straightforward, but ensure power is disconnected before servicing.