Goodman B1370189 Primary Limit Switch 200°F-30°F Thermal Safety OEM Replacement

The Goodman B1370189 is a critical safety component that acts as the "brain" for high-temperature thermal protection within your furnace. This genuine OEM primary limit switch is designed to monitor the temperature of the heat exchanger, ensuring that the system does not exceed safe operating parameters. It is specifically engineered for the GMS8, GDS8, and GMS9 furnace series. By detecting restricted airflow—often caused by a dirty filter or failing blower—this switch serves as a fail-safe that breaks the 24V circuit to the gas valve, preventing heat exchanger damage and ensuring the safety of your home.

Key Features

• Genuine OEM Part Number B1370189: This factory-calibrated safety device ensures the temperature trip points match the original design specifications of your Goodman/Amana unit.
• Precise Thermal Calibration: Features a 200°F "Open" and 170°F "Close" (30°F differential) setting, providing the exact sensitivity needed to protect the heat exchanger from warping.
• Fixes Intermittent "No Heat" Issues: Replaces aging switches that have become "weak" or "lazy," causing the furnace to cycle off prematurely before reaching the thermostat setpoint.
• Advanced Safety Monitoring: Provides a constant thermal watchdog for the combustion chamber, immediately halting gas flow if the internal cabinet temperature rises above the 200°F threshold.
• Gold-Plated or High-Temp Contacts: Engineered to handle thousands of cycles in high-heat environments without the internal contacts pitting or sticking.

Product Details

• Brand: Goodman / Amana / Janitrol
• Manufacturer: Goodman Manufacturing
• Part #: B1370189
• UPC/SKU: 662766113971 / 193031151954
• Shipping Weight: 1 LB ounces
• Voltage: 24 VAC (Control Circuit)
• Open Temperature: 200°F
• Close Temperature: 170°F (30°F Differential)
• Mounting Style: Standard Flange Mount
• Terminals: 1/4" Male Quick Connect

🛠️ HVAC Depot Pro Tip

"Check the Filter First"—before you replace the B1370189, verify that your furnace air filter is clean and that all supply registers are open. A primary limit switch usually trips because of an airflow restriction, not because the switch is "bad." During your Diagnostic Check, observe the furnace LED: if you see a "Limit Switch Open" code (typically 4 flashes), ensure the blower motor is spinning at the correct speed. If the filter is clean and the blower is running but the switch still trips, you likely have a cracked heat exchanger or a failing limit switch that requires immediate replacement.

Cross-Reference

• Superseded / Legacy Numbers:

  B13701-89, B1370189S, 107342-05

• Equivalent Numbers:

  L150-30, 36TX11, 20197711

• White-Rodgers / Emerson Equivalents:

  3F01-150 (Logic Series)

Model Compatibility

• GMS8 (Suffixes: 0453ANA, 0703ANA, 0704BNA, 0904BNA, 0905CNA, 1155CNA)
• GDS8 (Suffixes: 0453ANA, 0703ANA, 0904BNA, 1155CNA)
• GMS9 (Suffixes: 0453BXA, 0703BXA, 0904CXA, 1155DXA)
• DMS8 (Suffixes: 0453ANA, 0703ANA, 0904BNA, 1155CNA)
• DMS9 (Suffixes: 0453BXA, 0703BXA, 0904CXA)
• GCH9 (Suffixes: 0453BXA, 0703BXA, 0904CXA)
• GDS8 (Suffixes: 0453AXA, 0703AXA, 0904BXA, 1155CXA)