OEM Carrier Draft Pressure Switch 0.18" WC for Model PY4GNAB24040AA

This is the genuine OEM replacement draft inducer pressure switch for the Carrier PY4GNAB24040AA packaged unit. The pressure switch monitors negative air pressure created by the draft inducer motor to confirm proper venting before allowing the ignition sequence to proceed. When this switch fails or sticks open, the furnace or packaged unit will lock out before ignition — leaving you with no heat. Common symptoms include a draft inducer that runs continuously with no ignition, a blinking fault code indicating a pressure switch error, or a system that attempts to start and immediately shuts down.

• Specs: 0.18" WC (inches water column) set point | SPST (Single Pole, Single Throw) | Direct OEM replacement for part numbers HK06WC061 and superseding part HK06MB061 | Compatible with 24V control circuit
• OEM vs Generic: This is a factory-authorized Carrier part manufactured to precise pressure tolerances. Generic aftermarket switches often carry a ±5–10% pressure variance, which can cause nuisance lockouts or — worse — allow ignition under unsafe venting conditions. OEM accuracy matters here.
• Install difficulty: 2/5 — Power down the unit at the disconnect and thermostat before beginning. Tools needed: 1/4" nut driver, flathead screwdriver, and a short length of replacement rubber tubing (inspect the hose while you're in there). Photograph all tubing connections before disconnecting. The switch is typically secured by one or two screws near the inducer housing.
• Warranty: 1-year OEM manufacturer warranty. In-stock orders placed before 3 PM ship same business day from our warehouse.

Compatibility: Designed for the Carrier PY4GNAB24040AA packaged unit. This part also fits a wide range of Carrier, Bryant, and Payne furnaces and packaged units requiring a 0.18" WC draft pressure switch. Always verify the W.C. rating on your existing switch's label before ordering — using an incorrect pressure rating is the leading cause of pressure switch-related misdiagnosis. Questions about fitment? Our HVAC parts specialists verify compatibility before you order — just reach out.