Carrier LH33WP003 Circuit Board

For veteran technicians servicing Carrier rooftop units and furnaces, the Carrier LH33WP003 Integrated Circuit Board (IGC) serves as the central logic and timing hub for high-performance gas heating. This genuine Direct Spark Ignition (DSI) control board is engineered to handle the complete sequence of operation, including pre-purge timing, spark ignition, and gas valve management. Because the LH33WP003 is identical to LH33WP003A, it provides a seamless OEM replacement circuit board solution for a wide range of Carrier and Bryant commercial equipment.

The microprocessor-based controller monitors critical safety inputs, such as flame sensing, inducer motor Hall Effect sensors, and limit switches, ensuring 100% safety lockout protection in the event of an ignition failure. Diagnosing field issues is made efficient through its onboard LED status indicator, which provides clear flash codes for rapid troubleshooting of combustion and blower motor faults. Specifically designed for 24V control circuits and compatible with both Natural Gas and Liquid Propane (LP) systems, this board maintains precise 45-second pre-purge and post-purge cycles to optimize heat exchanger reliability and environmental safety.

• Direct OEM Compatibility: Installs as a drop-in replacement for Carrier LH33WP003 and LH33WP003A modules to ensure factory-spec timing.
• Advanced Diagnostics: Features microprocessor-based fault codes via integrated LEDs to shorten time-on-site during service calls.
• Full-System Integration: Manages the inducer motor, blower motor, and gas valve while monitoring all safety roll-out and limit switches.
• Precision Spark Ignition: Delivers consistent high-voltage ignition and rigorous flame sensing for dependable cold-weather startups.
• Universal Fuel Support: Fully compatible with both propane and natural gas furnace configurations.

Is the LH33WP003A different from the LH33WP003?
No, these part numbers are interchangeable. The LH33WP003A is the exact same integrated gas control (IGC) board and follows the same terminal layout and sequence of operation.

What does a flashing red LED on this board indicate?
The red LED is a diagnostic tool. A steady light indicates normal operation, while specific flash patterns point to faults such as a failed flame sense, a tripped limit switch, or pressure switch issues. Consult the service manual for the unit's specific code definitions.

Does this board support 115V or 230V applications?
The Carrier LH33WP003 typically operates on a 24V control circuit, but it is designed for use in systems with 208/230V line voltage motors, managing the power distribution for the inducer and blower fans.

Disclaimer: While we strive for 100% accuracy, product data and specifications are subject to change. Please contact our team to confirm compatibility or technical details before purchasing.