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The OEM Goodman 20162906 M4 primary limit switch is a factory safety control for the Goodman GCH90703BXAB gas furnace. This normally-closed thermal switch monitors heat-exchanger temperature and opens the circuit to shut off the burners if the furnace overheats — protecting the unit and your home from unsafe conditions. A tripped or failed limit switch is a common cause of short-cycling, no-heat calls, and blower lockouts.
This genuine Goodman OEM limit switch is calibrated to the exact trip temperature specified for your furnace's heat exchanger. Because a limit switch is a safety-critical component, matching the factory temperature rating is essential — a mis-rated generic switch can either nuisance-trip or fail to protect the unit. Choose OEM for correct calibration and peace of mind.
Moderate (2/5). Replacement requires removing two mounting screws and transferring the wire terminals. Cut power at the disconnect before servicing. Verify the switch temperature rating matches the original.