I have a 2001 Buick Century, my heater cycles between blowing hot and cold air. I have recently flushed my radiator as well as replaced the coolant. My temperature gauge rises to a point that the temperature light comes on, but then the heat starts working and the gauge returns to normal. The hoses are firm, showing no signs of engine overheating. Any help would be appreciated.

  • Before the heat starts working with the engine at operating temperature, are the heater hoses both the same temperature? or is one cooler than the other. I'm guessing you have one of the 3.x engines in your car. There should be two bleeders 7mm or 1/4", one on the thermostat housing and the other on the coolant crossover pipe that runs across the radiator side of the engine. What happens when you open the one on the crossover pipe with the engine running?
    – Ben
    Nov 10, 2017 at 0:40

1 Answer 1


You probably have air bubbles in the coolant, which were introduced when you flushed the system. You should bleed the cooling system. The exact procedure for bleeding is different for different engines, so you should look in the shop manual for your model.

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