OEM Carrier Draft Pressure Switch 0.18" WC for Model PY3GNAA30040AA

This OEM draft pressure proving switch is the factory-authorized replacement for the Carrier PY3GNAA30040AA packaged unit. The pressure switch monitors negative pressure created by the inducer motor to verify proper venting before allowing the ignition sequence to proceed. When this switch fails or sticks, the furnace will lock out entirely — often before the burners ever fire — leaving you with no heat and a blinking fault code on the control board.

• Specs: 0.18" Water Column (WC) set point | SPST configuration | OEM Part # HK06WC061 (superseded by HK06MB061) | Replaces Honeywell IS20224-5236
• OEM vs Generic: OEM pressure switches are calibrated to exact factory WC tolerances. Off-brand units with even slight WC drift can cause nuisance lockouts or — more dangerously — allow combustion with insufficient draft, creating a carbon monoxide risk.
• Install difficulty: 2/5 — Shut off gas and power before servicing. Tools needed: 1/4" nut driver, flathead screwdriver, manometer (recommended for verification). Disconnect the rubber hose port, swap spade terminals, reconnect hose, and confirm inducer pressure at startup.
• Warranty: 1-year OEM factory warranty. Ships same business day from our warehouse when ordered before cutoff.

Compatibility: Designed for the Carrier PY3GNAA30040AA packaged unit. Note that OEM part HK06WC061 has been superseded by HK06MB061 — both are included in our inventory as a direct drop-in replacement. Always verify the WC rating on your unit's wiring diagram before ordering. Our fitment team is available to confirm compatibility before you buy.