Actually Doug you do if you think about it. As you know the heater cores flow all the time!

Okay its weird to run heat on one side and AC on the other, but some things to know. First both the AC and heat, for a mechanical point, run all the time. The AC runs at 5% when turned off that ramps up using a PWM solenoid or something like that. This is why the AC compressor has no clutch, its always engaged even if just a tiny bit. So its alway flowing something. The heater core always flows too but always at 100% - which is stupid really since it WILL reduce AC efficiency by simply heating up the HVAC internally within the dash - but I digress.

So yes, if you are pushing air over the core it can certainly help with cooling the engine when running the AC on the other side. But also know that no matter how the dials are set, the HVAC system will balance things out too. It is impossible to have full heat on one side and full cold on the other. The system won't do it, it basically has limits on the difference between the two sides. And I think on the LR3 like other cars, the driver temperature **** has "override" built in. Meaning if put full stop to heat, the passenger then gets full heat no matter what its set to. Same for full cold. That last click of the dial is like driver priority. Although I never looked into if the LR3 for sure has this, all my other cars do.

So your theory could be plausible, that the heat on with air over the core helped cool the engine a little. But I kinda find that hard to think it would have that much of an impact, not enough to prevent an overheating vehicle. By the way, when you say overheating what exactly y do you mean? How high did the needle go?

Basically I tend to agree with Doug, you have an inefficient cooling system and the AC is simply bringing it out. Since you did the rest the fan clutch may be your best bet indeed. Keep us posted.

 

From the owners manual, I recall the maximum differential to be about 6 degrees between the dual climates. I don’t recall which overrides if they are set beyond those bounds, but driver would make sense.

 

Dakota hits me with a technicality 😆

 

I agree it is a bit weird to run heat on one side and AC on the other. But, very good to know that both are flowing at all times. I think that's what I was most curious about. Passenger side was still pretty cool even with the drivers heat on, but now I'm wondering if I had it on max. Anyway, it totally makes sense there would be a limit on the difference. It's good to know I should expect that.

The needle got to max for about 5 seconds at most. Initially I just pulled over and let the engine cool, limping home was when I figured out that keeping the heat running kept the dial at the middle. Drove it around once more to confirm, that time the dial got about 3/4 way, so it was still doing something weird. I tend to keep a close eye on the engine temp, after my initial issue (before the water pump/thermostat/radiator replacement, that time the needle reached the top of the dial for a only few seconds) and reading about some other problems on here it's not something I want to mess around with on this car at all, though on any car it's not exactly good. After that I tore into it and found the slipped belt.

New fan should be here this week so I'll see if that does it. Of all things I found a wiper pump leaking as well, ha. At least that was an easy one to figure out and get to. Not nearly as really critical though.

 

No where in your adventures did you mention an actual number for the temp. I don't trust the dash gauge for anything more than to let me know I have a problem. Did you use an diagnostic tool an get an actual temp when it is running correctly AND when the needle goes up?

Without a diagnostic tool with data logging, you are just guessing.

Jeff

 

In my experience, I haven't needed great data for the cooling system. It's either working, which means the dash needle is in the middle and stays there no matter what, or... there's a problem and it starts creeping up.
I do see how scan data would tell you sooner that you had a problem though.

 

I can see the added advantage of knowing the exact temperatures. Certainly would have helped determine any creeping problems previous to the gauge telling me, but unfortunately I don't have one. I'm sort of with tracyc though, I had an issues either way.

Update is the new fan showed up yesterday. Clear difference how it was spinning on the nut even before I installed it. After install it was obviously moving a ton more air after startup as well. Test drive went great too, was able to use full AC with no problem after it came up to temp. Sat with it at idle for about 10 minutes after driving as well with the AC on full and the needle never budged past the middle. Keeping my fingers crossed that was the only problem. Here's where knowing the exact temperatures would come in handy again, just to make sure. I might have to look into an extra tool at this point, but it looks like the new fan has things humming again so far.

 

Thanks for the update. Fingers crossed for you!