OEM Lennox Relay & Start Capacitor Kit — 12J90

The genuine OEM Lennox 12J90 relay and start capacitor assembly kit provides the extra torque needed to get a compressor or motor up to running speed. The start capacitor delivers a high-capacitance boost during startup, while the potential (start) relay disconnects that capacitor from the circuit once the motor reaches full speed — working together to ensure reliable, hard-starting performance in your Lennox equipment.

Symptoms of a failing start capacitor or relay include a compressor that hums but won't start, frequent tripping of the breaker, clicking or buzzing at the contactor, hard starts, and intermittent no-cool or no-heat calls. A bulged, leaking, or burnt capacitor and pitted relay contacts are clear indications this kit needs replacement.

Because the start capacitor's microfarad rating and the relay's pickup and dropout voltages must be matched to the motor, installing the OEM Lennox 12J90 kit is the safest choice. Mismatched aftermarket components can fail to disconnect the capacitor, overheat windings, and destroy the motor. This factory-matched assembly ensures correct starting characteristics and long-term reliability.