2005 Honda Accord Overheating when idling

Ok, this is kind of weird…here goes…

When it is cold outside and I want to turn my heat on in my car, it takes a loooong while for heat to be produced. I have to have the car moving at a high rate of speed before any heat is made. Even when it is turned all the way to the hottest setting it just spits out cold air. Here is the real problem. If I have the temperature on the heat and the car is idle, the temperature gauge on the instrument panel starts to move around to the RED side(meaning the engine is hot, right?) As long as the car is moving the gauge will stay in the BLUE(engine is cool, right?) As soon as I stop the car at a red light or sit in traffic(which is usually the case) sure enough the little temperature needle begins to make its way to the RED side. As soon as I move again, it normals again. I have taken this to several mechanics and they have said that they do not know what is wrong and they think that it may just be a faulty temp gauge(this does not seem right) I do not really know if the car is in fact overheating when the gauge starts its travels or if the car is fine and I just have something that is faulty. PLEASE HELP???

How many miles are on this Accord and what is the history of cooling system service?

The high temps when sitting still that cool down when moving are classic signs of a bad cooling fan system. I can’t imagine that the mechanics have not checked this though. So the mechanics who looked at it must have done something. Does the fan work? Did they measure the actual coolant temperature as the gauge climbs?

The heat issue is different. How old is that thermostat? Have you been losing any coolant? Have you actually checked the coolant?

The short story is that evaluating a coolant system is not rocket science. So if “several mechanics” have looked at it but can’t say what is wrong then you need to say exactly what they have done and what maintenance that system has had since the car was new.

Next time it heads to the red zone, turn on the AC and see if it goes back to normal. If it does, open the hood with the AC on and see if both fans are running. If one of them is not, then that fan is bad. If both are running, then the temp sensor for the fan is bad.

The temp gauge should not be in the blue under normal driving conditions, It should be somewhere between 1/3 to 1/2 way up the scale, between the blue and the red. If not, then you need a new thermostat, but this is a separate issue from overheating at idle.

If you live where it get really cold, have the coolant checked for its freeze point. If the coolant is freezing up in the system, it could cause both problems.

Your symptoms sound like you are low on coolant. It is very easy to have a cooling system that is low on coolant even though the plastic bottle has coolant in it. This can happen due to pinhole leaks, or a bad radiator cap or entrapped air in the system if a system has a fluid change and is not properly refilled.

This can cause many oddball symptoms.

The mechanics that I have taken it too have not even checked out the car, they only said that I could get a new thermostat and that is it. it is the same thermostat that has been in the car since new.

There are about 90k miles on the car. As far as a history on the cooling system, it has had all its regular scheduled maintenance but I have never had a flush or specific cooling system service. Would this be beneficial?

Thank you, I am going to take a look at under the hood tonight when the kids go to bed. I will let you know.

I will check this tonight and see if this is the problem. Thank you so much. I will post again asap.