2003 Buick V6 Engine Running Cold results in NO Heat


Old 01-19-14, 03:58 PM
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Location: Staten Island, New York
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2003 Buick V6 Engine Running Cold results in NO Heat

Helping a friend with his car. Only spoke to him over the phone about it.

2003 Buick Century, V6, low miles about 34,000 miles, started running cold and giving no heat. This morning before starting he checked the coolant level in both the expansion tank and the radiator and said both OK - radiator full to the cap. I suggested that the thermostat was stuck open but he told me that when he starts the car both fans come on right away at start-up. Dash temp gauge remains low. Could this be that the thermostatic switch which runs the fan is shot?

Thanks in advance for any info.
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Old 01-19-14, 04:26 PM
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Not sure to see connection between stuck t-stat and fans running. Capiche?
Tell him to check both upper and lower radiator hoses. Initially, one should be hot the other cold, after t-stat opens, one hot one slightly cooler. If not, stat stuck open. Better than closed actually.

Thermostat Problems

This is covered in the Overheating Problems article, but I'll touch on it here. If you find that you don't have enough heat coming through the vents, it could be because your engine’s thermostat is stuck open. If this happens, your engine will run much cooler than it should and you won't have good heat at the vents.

Don't just replace the thermostat if you don't have good heat. Look for other causes first. One way to check if your thermostat is working correctly is to feel the hoses going to the radiator. When the engine is at operating temperature, the top hose should be hot and the bottom hose should be cool, or cooler than the top hose. If both hoses are cool to the touch with the engine at operating temperature, your thermostat could be stuck open. The only way to really find out is to remove it and inspect it. If you find it's stuck open, replace it, bleed the cooling system, and recheck your heat output. Don't skip bleeding the cooling system. Remember the number-one cause of no heat is air in the cooling system. One of the main causes of air in the cooling system is not bleeding the air out after servicing the cooling system. I recommend original equipment thermostats for best results.

Fans should not run on cold. But even with that, good stat will maintain proper coolant temp.
Btw, radiator filled to neck does not mean much, as coolant sucks into the system when stat opens. Is expansion canister at proper level too?

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Old 01-20-14, 08:51 AM
Join Date: Sep 2013
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I would suspect stuck open thermostat too. If the stat is working properly it would not matter if the fans were on all the time or not. Some fans are designed to be on when ever the AC circuit is engaged. This also includes the defroster circuit.
Old 01-20-14, 07:48 PM
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