IMAGE COMING SOON
OEM Guaranteed
Same-Day Ship
30-Day Returns
Secure Checkout
The Goodman 20162906 M4 Primary Limit Switch is a genuine OEM high-limit safety control engineered for the AMH80604BNAA gas furnace and other compatible Goodman and Amana 80% AFUE models. This normally-closed thermal switch monitors heat-exchanger and plenum temperature, cutting power to the gas valve if the furnace overheats due to a restricted filter, blocked ductwork, or blower failure. A working primary limit is required for safe furnace operation.
OEM vs. Generic: Genuine OEM limit switches are calibrated to the exact trip temperature your furnace's control board expects, so they cycle correctly and pass safety checks. Aftermarket generics often use a wrong set point, causing nuisance lockouts or, worse, failing to trip. For a safety-critical control, OEM is the recommended choice.
Installation difficulty: Easy. Roughly 15–20 minutes for a competent DIYer. Turn off power and gas, remove the two mounting screws, transfer the wires one at a time, and reinstall. No special tools required. If you are unsure, have a licensed HVAC technician confirm the fault before replacing.