OEM Carrier Draft Pressure Switch 0.18" WC for Model PY4GPAA36090AA

This OEM draft inducer pressure switch is the factory-specified replacement for the Carrier PY4GPAA36090AA packaged heat pump/gas unit. The pressure switch monitors negative pressure created by the inducer motor to confirm safe venting conditions before allowing the ignition sequence to proceed. When this switch fails or sticks open, the control board cannot verify inducer operation and the system locks out — resulting in a no-heat condition with a pressure switch fault code. Common failure symptoms include the inducer running but the furnace never advancing to ignition, or intermittent heating lockouts especially in cold weather.

• Specs: 0.18" W.C. (water column) rating | Draft pressure proving / normally open | Replaces OEM part# HK06WC061 (superseded by HK06MB061) | Also cross-references Honeywell IS20224-5236
• OEM vs Generic: This OEM-spec switch is calibrated to the exact 0.18" W.C. trip point required by Carrier engineering. Off-spec generic switches with loose tolerances can cause nuisance lockouts or, worse, allow ignition under unsafe venting conditions.
• Install Difficulty: 2/5 — Turn off power and gas before servicing. Tools needed: 1/4" nut driver, flat-head screwdriver, needle-nose pliers. Note hose port orientation and wire terminal positions before disconnecting. Inspect pressure tubing for cracks or blockages while the switch is out.
• Warranty: 1-year OEM factory warranty against defects. Ships same business day from our warehouse when ordered before cutoff.

Compatibility: Designed for the Carrier PY4GPAA36090AA packaged unit. Also fits select Bryant and Payne models requiring a 0.18" W.C. normally-open draft pressure switch — verify your unit's data plate and existing switch rating before ordering. Not sure it fits? Our HVAC parts specialists verify fitment before you buy.