Lennox 59K21 Control Board Refrigerant If you observe constant dripping

If you observe constant dripping or a steady discharge from the relief valve port despite the checks being clean

When diagnosing a furnace pressure switch error or a failed draft inducer motor

this valve’s compact footprint and high-flow orifice deliver the performance precision required in the field

Common Questions & Technical Support: What is the best way to determine if my valve needs a rebuild or a new coil

Lennox 59K21 Control Board Refrigerant If you observe constant drippingThe Lennox 59K21 Control Board is a fundamental integrated ignition control module designed for high performance residential gas furnaces. As a high reliability "brain" for your heating system, this board manages the critical sequence of operations, including the furnace ignition control, inducer motor timing, and blower transitions. Technical data confirms that the 59K21 is identical to 59K2101, providing a direct OEM HVAC replacement part for