OEM Carrier Direct Spark Ignition (DSI) Control Board LH33WP003 for Model PY1PNA042120ACBA

This is the genuine OEM Direct Spark Ignition (DSI) Control Board for the Carrier PY1PNA042120ACBA packaged gas/electric unit. As the brain of the heating system, this microprocessor-based board orchestrates the entire combustion sequence — managing the spark igniter, gas valve, inducer motor, blower motor, and all critical safety sensors. When this board fails, common symptoms include the unit locking out after an ignition attempt, intermittent no-heat calls, fault codes flashing on the board's LED, or a complete loss of heating function with no response to a thermostat call.

• OEM Part Number: LH33WP003 (also supersedes LH33WP003A) | Direct Spark Ignition (DSI) type | Microprocessor-based combustion and blower control | Factory-matched timing, trial-for-ignition, and lockout sequences
• OEM vs Generic: This factory-original Carrier board uses exact firmware and safety timing calibrated for the PY1PNA042120ACBA. Aftermarket boards (e.g., ICM291) may function as drop-in replacements but can differ in lockout timing, fault code behavior, and long-term reliability under cycling loads.
• Install Difficulty: 3/5 — Photograph all wiring harness connections before disconnecting. Discharge any residual voltage and shut off power at the disconnect. Tools needed: 1/4" and 5/16" nut drivers, needle-nose pliers, phone camera for wiring documentation. Always verify gas valve wiring polarity. Recommended for qualified HVAC technicians.
• Warranty: 1-year OEM factory warranty against manufacturing defects. Ships same business day from our warehouse when ordered before 3 PM local time.

Compatibility: Designed for the Carrier PY1PNA042120ACBA packaged rooftop unit. Verify your existing board's part number against LH33WP003 or LH33WP003A before ordering. This is a DSI-type board — confirm your unit uses direct spark ignition (not hot surface ignition) by checking the existing board's label. Questions about fitment? Our HVAC parts specialists verify compatibility before you order — contact us and we'll confirm.