OEM Carrier Direct Spark Ignition (DSI) Control Board LH33WP003 for Model PY3PNA030040NB

This is the genuine OEM Carrier LH33WP003 Direct Spark Ignition (DSI) Control Board — the factory-specified replacement for the Carrier PY3PNA030040NB packaged rooftop unit. The DSI control board is the central intelligence of your unit's heating system: it sequences the inducer motor, fires the spark igniter, opens the gas valve, verifies flame presence, and orchestrates the blower motor — all while continuously monitoring safety limit switches and pressure switches. When this board fails, symptoms typically include a no-heat lockout condition, the unit attempting ignition and immediately faulting out, erratic blower behavior, or a complete failure to respond to a heating call from the thermostat.

• Part Number & Type: Carrier OEM Part # LH33WP003 (also supersedes LH33WP003A) | Direct Spark Ignition (DSI) microprocessor-based control board
• OEM vs Generic: This is the genuine factory-authorized Carrier board — engineered to exact OEM tolerances for the PY3PNA030040NB. Aftermarket substitutes may lack precise ignition timing sequences (pre-purge, trial-for-ignition, retry, and post-purge cycles) matched to your unit's heat exchanger design, risking nuisance lockouts or premature component wear.
• Install Difficulty: 4/5 — Requires disconnecting 24V control wiring, line-voltage blower and inducer leads, and flame sensor/spark igniter harnesses. Always cut power at the disconnect before beginning. Tools needed: flathead and Phillips screwdrivers, needle-nose pliers, smartphone camera (photograph all wiring before removal), and a multimeter to verify 24V at the transformer secondary before condemning the board.
• Warranty & Shipping: Backed by Carrier's OEM factory warranty. In stock — ships same business day from our warehouse so your equipment is back online fast.

Compatibility: Engineered for the Carrier PY3PNA030040NB packaged rooftop unit. Verify your existing board's part number on the board label or your unit's wiring diagram before ordering. Cross-references include superseded suffix variant LH33WP003A. Need fitment help? Our HVAC parts specialists confirm compatibility before you buy.