97 Grand Am GT Thermostat

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  #1  
Old 12-29-06, 07:05 AM
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97 Grand Am GT Thermostat

I am having a problem with the heat coming into my vehicle where it is warm when I'm standing still but cools off when the vehicle moves. I checked the thermostat to see when it opens by feeling the hose going into the thermostat and it stays cools until the engine warms up and then becomes hot. I'm assumming that means the thermostat is staying closed and then opens. Since the air from the heater is cool when the car is moving, could it be that the thermostat stays open even though it operated correctly at first? This happens each time I start the car when it's cold. The temperature gauge gets into the normal range (I think about 180 deg F) and remains the same whether moving or not. Could it be that ther heater core isn't letting enough water through to heat good? Since the air is hot when not moving, that doesn't seem like the problem but you guys are the experts.

If it is the thermostat, how hard is it to change and does the coolant need to be drained before disconnecting the radiator hose or is the thermostat high enough where I don't have to drain the system?

Thanks for your help
 
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  #2  
Old 12-29-06, 10:12 AM
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Experts?????

You probably have a marginal heater core. The logic is that when you are sitting still, the outside air moving through the system would be less and the heater core works well enough. When you start moving, with the heater control on heat, you start introducing more of the outside air and the core can't warm it.

It would not be the thermostat if you have a solid 180 degrees with the engine warm.

Try setting the air control to max AC which should shut off the outside air. You may have a Recirc Air setting. Go to one of those and see if the air gets warmer for you.

The other thing you can try is to reverse the coolant lines going to the core. That will often unplug the core. Also, never hurts to change antifreeze and flush the system.

Hope this helps,

Bob
 
  #3  
Old 12-29-06, 01:19 PM
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Replace thermostat and flush cooling system.
 
  #4  
Old 01-02-07, 10:34 AM
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I tried putting the air conditioning on Max and the air was still cool so does that indicate poor heater core circulation?
 
  #5  
Old 01-02-07, 11:38 AM
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Have you tried getting a coolant flush like I told you?

If the thermostat is broken then the coolant is trapped in the radiator, heat maybe better when sitting idle, but, when car starts moving, the cold outside air hits the radiator cooling down the coolant, this producing cold air in the vehicle. The coolant needs to circulate through the whole system to get hot.

If there is a clog, then the hot coolant is not getting to the core, or there is a clog in the core itself.

Feel the two heater hoses going into the firewall, they both should be hot if working properly.

If both hoses are cold, then you have a clog or bad thermostat.

If one hose is hot, and the other cold, then you have a clog in the heater core.
 
  #6  
Old 01-03-07, 10:26 AM
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Check and make sure the heater control valve is open when the heat is on.
These valves work on vacuum and often fail.
You could also remove the valve to make SURE your getting constant hot water through the core.
 
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