Hi..

I'm hoping someone has had a similar experience to mine and can give me a few ideas. I have a 1996 Dodge Grand Caravan LE with a 3.8L that overheats while doing city driving on hot days while running the air conditioner. I know that it actually does get hot because the A/C performance drops way off when the gauge gets up there close to the "H" mark. If I shut off the A/C it will work it's way back down.

It has a nearly new radiator, two new aftermarket fans, (the whole fan shroud assembly etc.), newer water pump, and I believe I pressure tested the radiator cap. I have no cooling system leaks.

I have no water in the oil. I'm pretty sure the head isn't cracked or anything. The exhaust is clear and the oil is not milky. I don't lose fluid either.

I hooked up a MAC Mentor analyzer and tested the fan relay. It toggles on and off just as it should. Also, I reved the engine and watched the PWM fan speed go from about 30% all the way 100%. I let it drop to an idle and the PWM speed gradually droped back down to around 30%.

On a normal day or when driving at freeway speeds it holds the correct engine temperature while running the A/C. The A/C under those conditions blows cold.

If anyone has any similar experiences with successful resolutions or ideas etc., I'd love to hear from you.

I'm thinking of taking it to a radiator/cooling/AC shop and having the coolant circulation tested. I would assume they can measure the flow. I would think their flushing machine might measure the volume they can put through the system. I was hoping they can also meansure what the water pump will put through the system at temperature too.

Before I do that, I want to make sure I've exhausted all the DIY troubleshooting options. I am perpetually "under-funded"... Anyone else have problems like that? Finding extra money seems more challenging these days on a single income while supporting 5 others and myself!

Thanks for taking the time to read over this post.

 

I don't know know where you live, But when I drive from north california to south california. There is a pass called the grape vine. On very hot days you can see a lot of cars and trucks on the side of the road from overheating. There are signs that ask the driver's to turn out the A/C when climing the pass. Also when you are in traffic the car or truck maybe blocking some of your air flow thru the radiator or you have some debris between the radiator and condensor. If temp is running normal on other days that are not so hot, I would guess the very hot days that when you have problems with the cooling system. So you may not have a problem. When in traffic, roll the windows down and turn the A/C off and see how the temp goes up. If the cooling system doesn't start to overheat, then the A/C is putting too much of a load on the cooling system.