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The genuine OEM Lennox 74H01 Potential Relay controls the start capacitor circuit on your compressor. During startup it keeps the start capacitor in the circuit to provide the extra torque needed to get the compressor spinning, then drops the capacitor out once the motor reaches running speed by sensing back-EMF voltage. It is built to the exact coil voltage and contact rating specified for your Lennox condensing unit.
Common failure symptoms: A failed potential relay commonly causes hard starting, a compressor that hums but won't start, repeated tripping on overload, or a start capacitor that burns out prematurely. Pitted or welded contacts and a weak coil are typical failure modes that leave the start capacitor stuck in or out of the circuit.
Why OEM matters: The OEM Lennox 74H01 relay is matched to the pickup and dropout voltages your compressor and start capacitor require. A wrong or generic relay can leave the start cap engaged too long, overheating and destroying the compressor windings. Installing the factory-specified relay protects your compressor investment and restores dependable single-phase starting.