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Thermostats
Heater Cores and Blower Fans
Car Heaters
Overheating (Engines)

Why would the car overheat but no hot air come from the heater?


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2015-07-14 15:05:21
2015-07-14 15:05:21

You didnt say if the water pump was changed. No hot air means no circulation.

AnswerBrittany, You have 2 symptoms of a larger problem. It is like you said "I have a terrible headache and black eye." What happened was you missed the ball and it cracked you in the head.

Anyways, Coolant is a fluid that keeps a car from getting too hot among other things. If there is low coolant the car will overheat. When the coolant ciculates through the engine it will also go through a thing in the dash that is like a small radiator called a heater core. A fan or blower move air through this part and pushes the hot air from the heater core into the passenger compartment. This heater core is usually the highest point of the coolant flow. Since fluid seeks it's lowest level, the heater core is the first to lose the hot coolant. Therefore your blower blows accross a cold heater core and gives you cold air.

If you don't have a leak, then when the thermostat was replaced, the coolant may have not been bled of the air in the system.

I would first fill the coolant and check for any leaks first. There is a common problem with the Buick centuries if you have a 3.1 motor. The intake manifold gasket is common for leaking.

In any event, don't run the engine if it goes into the red. Overheating can cause headgasket problems. See othe posts regarding this issue.

Let me know how you make out.

AnswerGlad to hear your problem was resolved.

The heater core does not need to be removed to be checked. If the hose going into the heater core is hot and the one coming out is cold, the tells you it is retricted. Another way to verify is to remove the hoses going to the core, hook up one without installing into the car and run it. It should get hot-very hot, and then see how hot the hose is coming out of the core is like now.

AnswerIf this person that replaced the thermostat put it in backwards this could cause the car to overheat and the heater not to get hot. EzForJesus AnswerSimple - It is low on radiator fluid (water or anit-freeze).

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Hose going from engine to heater core may have burst. Check all your coolant hoses for leaks.

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An air bubble will stop the coolant from flowing and keep water from the heater core. The engine could also overheat, depending on where the bubble is.

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possible clogged or damaged heater core

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You should check your water level. It's low, and you have a leak. Get someone to check it for you. The heater in your car works off the water from your radiator, no water in the radiator will over heat the engine ergo top up the water. Could also be low antifreeze level causing water in radiator to freeze making the engine overheat and the heater to blow cold air. You have an airlock. If you have a system with expansion/filler tank then check the return pipe is not blocked. These systems bleed themselves if there are no blockages. Mine was because the impeller in the water pump had disintegrated to the point where it would not move the water. The water would overheat, but the hot water would not get moved into the heater core to blow hot air. I replaced the water pump and it all works now.


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