OEM Carrier Draft Inducer Pressure Switch 0.18" WC for Model PY3GPAA42090AA

This is the genuine OEM replacement draft pressure switch for the Carrier PY3GPAA42090AA packaged gas unit. The pressure switch proves that the inducer (draft blower) motor has established proper negative pressure in the heat exchanger before allowing the ignition sequence to begin. When this switch fails or is stuck open, the furnace control board detects no proof of draft and locks out the system — preventing the unit from ever reaching the ignition stage. Common symptoms include a furnace that attempts to start, the inducer spins up, but the system never progresses to spark or gas valve opening, often accompanied by a fault code indicating an open pressure switch.

• Specs: 0.18" Water Column (W.C.) | SPST (Single Pole, Single Throw) | Normally Open | Replaces OEM part numbers HK06WC061 and superseded HK06MB061 | Also cross-references Honeywell IS20224-5236
• OEM vs Generic: This OEM switch is factory-calibrated to the exact 0.18" W.C. setpoint required by the Carrier PY3GPAA42090AA control board. Generic aftermarket switches frequently drift outside tolerance, causing nuisance lockouts or — more dangerously — failing to detect a blocked flue, which is a serious safety risk.
• Install difficulty: 2/5 — Shut off gas and power before servicing. Tools needed: Phillips and flathead screwdrivers, needle-nose pliers. Locate the switch on the inducer housing, note the hose and wire connections, swap the switch, and restore power. A multimeter can confirm continuity when the inducer is running.
• Warranty: 1-year OEM manufacturer warranty. In-stock orders ship same business day from our warehouse.

Compatibility: Engineered as the exact factory-specified replacement for Carrier model PY3GPAA42090AA packaged gas/electric units. This part is also compatible across select Bryant and Payne models sharing the 0.18" W.C. specification — verify your unit's data plate and existing switch rating before ordering. Our team is available to confirm fitment prior to purchase.