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The Goodman 20162906 is a genuine OEM M4 primary (high) limit switch built as a direct-fit replacement for the WFM18090S5CXCB gas furnace and compatible Goodman/Amana models. Mounted on the heat exchanger bulkhead, this temperature-sensing switch monitors supply-air heat and interrupts the burner circuit if temperatures exceed the safe setpoint — protecting against overheating from a dirty filter, failed blower, or restricted ductwork. Auto-reset operation restores the circuit once the furnace cools to a safe range.
Our OEM Goodman M4 switch is calibrated to the precise open/close temperatures matched to this furnace's heat exchanger and blower design. Generic limits with different setpoints cause short-cycling on limit or fail to protect the exchanger. For a primary safety control, use the correct OEM part.
Easy (2/5). Disconnect power and gas, remove the two mounting screws and wire terminals, and install the new 20162906 in the same orientation on the heat-exchanger panel. Restore power and confirm normal cycling. Replace any dirty filter that may have caused the original trip.