sorry guys I have been out of the rover for the last month so not been on here much, but since it is my primary again I must ask this. so I stopped driving the rover because 115 degrees without A/C is too hot for my family, and since the A/C causes the truck to overheat I can't use it. I know the A/C causes the truck to overheat because I can drive it without A/C and its fine. I am under the impression that whatever the problem is with the A/C it is causing the condenser to get to hot, in turn sending already heated air through the radiator and not allowing the engine to cool properly. I hooked up my A/C guage to the low side of the system today to see if it was low, and the pressure was actually really high (around 75 PSI). I was not sure if anyone (that may know more than me about A/C systems) may know what may cause this to happen. The A/C does work but not really well, all 3 fans work as they should (have the heavy duty chevy clutch fan) compressor engages, etc. any other thoughts? I was thinking something is clogged up like maybe the expansion valve or something.

 

hmm....


id take it to a shop. a/c is the one thing i hate.

 

Well...it cant hurt to have the a/c checked out and working properly...but I think the problem is more likely a partially clogged radiator.....it works "sufficiently" but not enough flow when the load of the a/c is put to it....

 

the problem is I flushed the cooling system, replaced a good water pump, thermostat, a bad e fan and a bad clutch fan and I am still in the exact position I was in when I started (maybe a little better) I have determined there is a problem with the A/C, and I read the pressure readings last summer and they were where they should have been (now it's high). my view on this is no matter how fast you blow super hot air through a radiator it will not cool the fluid down inside, but regardless I am still under the belief the cooling system is working correctly (and I really don't want to keep throwing money at something that I believe works as it should) especially since I bought a $2500 second vehicle last month that now has a blown engine.

anyways all I am asking is if anyone who knows A/C systems could give me the reasons why an A/C condenser would get too hot, I kind of know how an A/C system works but I don't fully understand what would happen if each component starts to fail. Such as a high or low pressure reading, insufficient cooling, too much heat transfer to the condenser, or in my case all 3!

 

I can see your dilema( and I'm not an a/c authority)...but I have to ask.....
how did you flush the rad ?.......quite often the garden hose method is not enough, it may need to come out and be professionally "boiled out" .
Also I have been told by a couple of techs that most a/c systems have high pressure & low pressure switches which will shut off the compressor if/when the pressure gets too great (or not enough). are the finns on the condenser good & clean ?

 

there does not appear to be any airflow restriction, and I did the flush with a flush kit and a garden hose. but the truck runs fine without the A/C on all day long. I have only noticed the A/C shut off once this summer on its own at least that's what I perceived happened, don't remember exactly what led me to believe the compressor shut off, but the air did get warm for about a minute. I know when the truck is running with the hood open I can feel alot more heat blowing through the radiator with the A/C on then I do when it is off, which is where I drew my conclusion.

 

Think about the air temps crossing your evap coil (inside), there's a direct relationship be tween air temp over coil & evap pressures.

I wouldn't bat an eye if my in-car temp was 95 and I had 75psi in the coil, it will drop as the car cools inside.

When I charge an auto a/c, I've got a blower in front of the grille simulating 30mph, to keep the condensor temps manageable.

Anytime your driving with the a/c on, the condensor heat is going thru' your rad, but they're designed for that, if you overheat, there's other issues.

The best flush is to remove it, take it to a rad shop. (few of us do that)

My last flush, (probably the fourth in six years) was with prestone radiator cleaner, I couldn't believe the crap that came out, and I cheated (2hrs instead of two days driving around)

I'll do it again this fall, only right.

luck,greg

 

Take it to the radiator shop. Get it rodded out. I put cleaner in mine, but it will not unclog a radiator.

 

Myself and a few other pretty knowledgeable people have decided that the problem may not be in the cooling system but more of a problem causing the engine to get too hot. we are leaning at a timing issue, but I don't feel confident in diagnosing it myself so I am taking it to a local LR master tech here in town who owns an indy shop. I will post the verdict when I have it.

 

I have an issue with my 98 right now. Sounds a lot like your issue but the trucks not overheating at all. At first we found one of the electric fans was stuck, so I replaced it and took the time to really clean out the fins of the rad. The system worked after that kind of, you could feel cold air, but it was no where near enough to cool down the truck. I'm leaning toward an expansion valve myself, and from what I understand it's a pretty detailed job to replace. (My local shop doesn't even want to do it cause his book is telling him 10 hours labor alone)

It's a pain but I'm going to have to dig out the Rav and start tearing the system down once I'm done working on my 96. I can't use the truck as it is with my family cause we sweat to death in it.