Greetings,
I am new to this forum and hope I can find some assistance...

I have a 1999 Galant V6. I recently noticed that my car starts to overheat when stopped and in idle. If I begin to move, or even if I just put it in park and give it gas, the gauge immediately starts to go down to where it should be.

In addition, the A/C also only blows cold air when I am giving it gas in park or moving. In idle, it blows warm air.

I checked both the fan for the A/C and the fan for the radiator, and they both run perfectly. In fact, the radiator fans seems to run excessively--more often and with greater intensity than it used to. I notice this when stopping after running the car for awhile. The loudness of this fan is noticeable.

The coolant level is right where it should be, and I have at least a 50/50 mixture of coolant/water. The radiator cap looks good. And I think the temperator gauge has recently been replaced. I am not noticing any coolant leaks anywhere.

I warmed the engine and felt the top and bottom radiator hoses to see if both were hot, indicating good flow of coolant, and they were both hot.

I have spent a lot of time recently searching this forum to see if there have been any similar issues. I found one similar problem, here: http://www.mitsubishi-forums.com/t14405-st...alant-4-cyl.htm

His situation is a little bit different than mine, but his resolution was to get the water pump replaced.

Any insight into this issue? Does it sound like a water pump issue?

I would think that could be the problem with the overheating, but would that affect the A/C?

Any help anyone can provide is greatly appreciated. Thanks so much!

Well it can be a flow issue with the radiator , when idling the flow of water is alot lower than at higher rpm's. If there is restriction in the radiator or the thermostate opening and closing restricting the flow this could be the case. If the radiator has flow issues and the cores are not circulating flow as needed , when teh car is at idle the water is not moving freely thru the radiator. As why when yu press on teh accelerator a little to raise the rpm the extra rpm turning teh water pump adds more force to give a better water flow. Since the air conditioning condensor sits right in front the radiator , the extra heat could keep it frum cooling efficientlly. Also check to see if there is a lot of debris, built up dust , dirt , leaves and other things that can accumilate in front of the radiator and condensor. I had one case about 6 years ago on a 97 Galant Super VR-4 (which is the same body style as yurs) he had cooling problems and high boost temps and also a/c cooling issues. The result was , lots of dirt and leaves and sum mud had accumilated inbetween his radiator and A/C condensor causing air restriction. Altho the fans were very audible and obviouslly on they were not pulling much air thru teh condensor and radiator cause of all the debris it had lodged in between them over the years. Thus teh radiator fans also work in cooling off teh condensor, if it cannot cool of the condensor the line pressure will be to high and is why there is a high side pressure line switch , when the pressure gets high it shuts the compressor off. In ways it seems kind of yur situation, at idle and park there is no air flowing thru teh condensor so it gets hot and the pressure gets high and the high pressure switch shuts the compresser off, but when yu get moving again and a flow of air frum teh front of the car moves thru it , enough to cool the condensor and drop they pressure teh compressor kicks back on. First thing yu need to do is unbolt the upper retainers of teh radiator , and then move it gentelly toward the engine to inspect inbetween to see if there is alot of debris restricting teh air flow.

I hope this helps.

Excellent! I will definitely try to check for debris. It would be great if it was an easy fix like this rather than the complex water pump replacement job.

Although if there were debris, that wouldn't necessarily explain why it works out sitting still in park, with me giving it additional gas.

I'm wondering if maybe I should drain the coolant and flush the radiator too...

But I will post back with a reply when I try it.

Thanks for your help.

yes i would flush the radiator also , take it off , that would give the opurtunity to remove it frum the car and to clean the front area , i see lots of radiator accumulate debris oil dirt , leaves etc over time between there that people never notice. The reason it may bring the temp down when yu raise the rpm may be because at idle the water flow rate is very low, and not having a wide flow or water being cooled because of possible poor flow of air thru the radiator. but when yu raise the rpm a little , it streams more a flow of water passing thru the radiator , and transfer enough water frum the radiator to teh engine to bring the temp down.