OEM Carrier Pressure Switch 1.81" WC SPST for Model PG9MAA048100AFKA

This OEM pressure switch (part number HK06NB123) is the factory-specified inducer proving switch for the Carrier PG9MAA048100AFKA gas furnace. The pressure switch monitors the negative pressure (vacuum) created by the draft inducer motor before allowing the control board to advance to the ignition sequence. When the switch fails — or the inducer fails to develop adequate draft — the furnace locks out before a single spark fires, protecting the heat exchanger and flue system from dangerous backdrafting. Common failure symptoms include a furnace that starts the inducer but never advances to ignition, a blinking fault code indicating a "pressure switch open" error, or a furnace that short-cycles immediately on a call for heat.

• Specs: 1.81" WC (inches water column) setpoint | SPST (single-pole, single-throw) configuration | Two wiring terminals | Two hose ports | Factory-matched switching accuracy
• OEM vs Generic: This OEM switch is calibrated to the exact 1.81" WC trip point required by the Carrier PG9MAA048100AFKA. Generic pressure switches with ±5–10% tolerance can cause nuisance lockouts in cold weather or, worse, allow operation under insufficient draft — a combustion safety risk.
• Install Difficulty: 2/5 — Shut off power and gas before beginning. Tools needed: 1/4" nut driver, small flathead screwdriver, and a manometer (recommended to verify draft after install). Disconnect the rubber hose and two wire terminals, swap the switch, and re-verify operation on the next heat call.
• Warranty & Shipping: 1-year OEM manufacturer warranty against defects. Ships same business day from our warehouse — order before 3 PM local time for next-day delivery eligibility.

Compatibility: Designed for the Carrier PG9MAA048100AFKA gas furnace. Note that OEM part HK06NB123 has been superseded by HK06NB124 — both share the same 1.81" WC specification and are functionally identical for this application. Always verify the WC rating on your existing switch's label before ordering. Our fitment team is available to confirm compatibility before you place your order.