OEM Lennox Contactor DPST 24V 40A — 72L12

The genuine OEM Lennox 72L12 (also cross-referenced as 20394903) is a double-pole, single-throw (DPST) contactor rated for a 24-volt control coil and 40 amps per pole. It acts as the electrically controlled switch that energizes your condenser's compressor and outdoor fan motor whenever the thermostat calls for cooling, carrying the high-voltage load without exposing low-voltage controls to it.

When a contactor begins to fail, the symptoms are hard to miss: pitted or welded contacts that leave the compressor running constantly, a loud chattering or buzzing hum from the coil, an outdoor unit that won't start, or burnt and discolored terminals. A weak or shorted 24V coil can also prevent the unit from responding to the thermostat at all.

Choosing the OEM 72L12 matters because the contact ratings, coil voltage, and terminal layout are matched exactly to your Lennox equipment. Generic substitutes may have different pull-in voltages or amperage ratings that shorten compressor life or cause nuisance failures. This factory-spec part ensures proper fit, correct switching, and full rated durability for your Lennox system.