the "0" (zero) and "O" are often used interchangeably in field service catalogs for this specific Warrick liquid level control

Carrier HC41AE232 1/3HP 1100RPM Fan Motor

this part serves as a directional check mechanism within the combustion or venting assembly

and Armstrong units to maintain original factory performance ratings

Carrier HN67LM105 Control Board 318820-201 the "0" (zero) and "O"The Carrier HN67LM105 Compressor Protection Module (CPM) Control Board is a critical OEM component designed for high performance HVAC compressor protection and precise system management. Built with advanced microprocessor technology, this ECM compatible control board monitors vital operating parametersincluding temperature, current consumption, and oil pressureto prevent catastrophic equipment failure. As a direct replacement for legacy models like