The RIB2421C is UL864 listed

Common signs include the furnace blower running continuously without heat or the burners shutting off prematurely before the thermostat setpoint is reached

resolving status code 22 or abnormal flame-proving signal errors without the need for field modifications or bracket adjustments

the issue may lie with the UCM or the inlet valve

offering a 40°F differential that prevents short-cycling

Johnson Controls A99BB-200 Temperature Sensor The RIB2421C is UL864 listedThe Johnson Controls A99BB 200 is a high precision PTC silicon temperature sensor specifically engineered for reliable monitoring in professional HVACR applications. As a veteran grade refrigeration temperature sensor, it features a 6 1 2 foot PVC cable and a stainless steel sensing bulb to withstand moisture heavy environments like walk in coolers and display cases. This model serves as the designated A99CB 200 replacement; however, please note that