Lennox 33J88 Pressure Switch

The Lennox 33J88 Pressure Switch is a critical safety component designed for precise draft monitoring in high-efficiency gas furnaces. Rated for a set point of 4.50" WC, this SPST (Single Pole Single Throw) switch provides reliable circuit closure to the control board once the inducer motor establishes the required negative pressure. This part is a direct factory replacement for Lennox model 33J8801, ensuring a drop-in fit with existing mounting brackets and vacuum line configurations. Engineered for the 80MGF2 series and other compatible Lennox air handlers, it features a standard compression connection for a secure, airtight seal that prevents nuisance trips and pressure loss.

For field technicians, the Lennox 33J88 serves as an essential furnace pressure switch replacement when diagnosing "open pressure switch" error codes or combustion air inducer failures. Its robust diaphragm construction is built to withstand high cycles in demanding residential and commercial HVAC environments. By maintaining precise 4.5 inch water column calibration, this switch ensures the combustion process only initiates under safe venting conditions, effectively protecting the heat exchanger and residential air quality. When performing maintenance, always verify the integrity of the vacuum hose and collection box ports to ensure the switch receives an accurate delta-P signal.

• OEM Compatibility: Original equipment replacement for Lennox 33J8801 and specific 80MGF series furnaces, ensuring electrical and mechanical alignment.
• Precision Calibration: Factory-set at 4.50" WC to match original system specifications for safe burner ignition.
• Durable SPST Configuration: Simplified Single Pole Single Throw switching logic for dependable 24V or 120/240V control circuit integration.
• Leak-Proof Connection: The integrated compression connection protects against air bypass, reducing diagnostic callbacks.

How do I troubleshoot a 33J88 switch that stays open?
First, inspect the vacuum hose for cracks or moisture and ensure the port on the inducer or collector box is clear of debris. Use a manometer to verify if the inducer is pulling at least 4.50" WC; if the pressure is sufficient but the switch remains open, the internal diaphragm may be failed.

Will this part replace the Lennox 33J8801?
Yes, the 33J88 is functionally and physically identical to the 33J8801 and can be used interchangeably without modifications to the wiring or pneumatic lines.

What causes a pressure switch to trip prematurely?
Premature trips are often caused by restricted flue venting, a failing inducer motor, or moisture accumulation in the pressure tubing. Always check the vent termination for obstructions before replacing the switch.

Disclaimer: While we strive for 100% accuracy, product data and specifications are subject to change. Please contact our team to confirm compatibility or technical details before purchasing.