OEM Carrier Draft Pressure Switch 0.18" WC for Model PY4GNAA24040AA

This OEM draft pressure switch is the factory-specified replacement for the Carrier PY4GNAA24040AA packaged unit. The pressure switch monitors negative pressure created by the inducer motor to confirm proper venting before allowing the ignition sequence to proceed. When the switch fails or becomes stuck, the control board cannot verify safe venting conditions — resulting in a hard lockout with no heat, typically before the burners ever fire. Common failure symptoms include the inducer running continuously with no ignition, a flashing fault code indicating pressure switch failure, or the system shutting down within the first 30 seconds of a heat call.

• Specs: 0.18" W.C. (water column) rated | Single-port draft sensing | Normally open (NO) configuration | OEM part number HK06WC061 (superseded by HK06MB061) | Manufactured by Honeywell for Carrier
• OEM vs Generic: This is the factory-matched OEM switch calibrated to the exact 0.18" W.C. trip point required by the PY4GNAA24040AA control board. Generic substitutes often carry wide pressure tolerances that can cause nuisance lockouts or — more dangerously — fail to detect a true venting restriction.
• Install difficulty: 2/5 — Disconnect power before servicing. Tools needed: 1/4" nut driver, flat-head screwdriver, and a manometer (recommended to verify inducer pressure post-install). Photograph or label the vacuum hose connection and wiring spade terminals before removal. Inspect the hose for cracks or blockages before installing the new switch.
• Warranty: 1-year OEM factory warranty. In stock and ships same business day from our warehouse.

Compatibility: Designed for the Carrier PY4GNAA24040AA packaged unit. Also cross-references with Bryant and Payne models sharing the same 0.18" W.C. pressure switch specification. Verify the W.C. rating printed on your existing switch label before ordering — using an incorrect W.C. rating can result in persistent lockouts. Questions about fitment? Our HVAC parts team confirms compatibility before you order.