Runs hot with AC turned on???

I've tested this twice on the same stretch of highway, headed straight into the wind.

It will run at 210 anytime, moving or not. As soon as I turn on the AC, the temp starts to creep up past 240+

I've owned this rig since 2004 and have never put refrigerant in it, but would that have anything to do with making the engine run hot? Is this a heater core issue? This is a 1992 model with 170K miles on the odo.

I just put this thing back together...got my radiator repaired, installed a new water pump and thermostat.

Is this just a coolant flow issue that is amplified when the AC is running?

Is your aux fan running when the a/c compressor runs?

Does it have a 2-core radiator or has a PO replaced it with a single-core?

Yes, the electric fan runs when AC is turned on.

This has a CSF 3core radiator that was repaired...
motor mounts gave out durin a wheelin trip and the fan got into the radiator.

As soon as I turn the AC off, the temp starts to creep back down to normal range.

I had the same issue after a radiator replacement. The wires for the aux fan got swapped and the fan blew the wrong way. Every time I would idle with A/C on the temps would scream up, and go back down when I started moving again. Took me nearly a year to figure out the issue. It's probably not a common problem, but it sounds exactly as you describe.

Easy enough to test for a reversed fan--engine off, jumper power/ground to the fan, check air flow.

There could be a minute chance that you have a crossed/shorting circuit and the temperature gauge is being getting some kind of resistance feed back when the a/c is on, falsely indicating raising temperatures.

Sounds like a bad fan clutch.

A bad fan clutch? Really, I don't even have a mechanical fan in my XJ and I don't have any overheating issues with just a single electric fan.