Buick Century high speed cooling fans not starting while low speed fans function with air conditioning on Buick Century

Some Buick Century owners report experiencing issues with high-speed cooling fans not starting while low-speed fans operate with the air conditioning. This problem may stem from a malfunction in the cooling system, potentially due to a faulty high-speed relay. Owners are advised to check the cooling fan fuses for integrity and test the continuity of the cooling fans with an ohm meter. Swapping the low and high-speed fan relays can help identify if the relays themselves are at fault. Additionally, the Engine Control Module (ECM) is responsible for commanding the low-speed fans based on engine coolant temperature and A/C refrigerant pressure, which may affect overall fan operation. The ground path for the cooling fans is managed by the Powertrain Control Module (PCM), which can result in both fans running at low speed or at high speed depending on the ground path supplied. It's also important to check the functionality of the coolant temperature sensor, as it influences fan speed control. Some owners find that directly testing the fan with a 12-volt power source can help ascertain its functionality, followed by a thorough inspection of fuses, relays, and the coolant sensor. Lastly, electric radiator fans in the Buick Century may have a limited lifespan, necessitating servicing or replacement, particularly if they operate with an oil-filled fan clutch.