On my 92 240 when I run the a/c on a day that is 90 or hotter everything will run fine but randomly especially at a stop i will notice my temp gauge jump to just below the orange. I have verified that my electric fan is cutting on when I turn the a/c on but haven't verified if it's still running once it starts overheating. I do know that if I turn the a/c off and get at a constant speed it will cool down and go back to normal.

I have searched a few threads here that say it could be a temp control bypass? I also have the high pressure switch already jumpped but was wondering if maybe the relay or the fan itself might be flaking out or something else totally different?

 

Honestly? Without seeing the car, I'd suspect 1. Thermal fan clutch inefficiency 2. Radiator needing to be flushed 3. Belts need tightening
The overheating seems to be worse with a/c and worse at idle. A $20 hand held non-contact thermometer of the IR type could quickly tell you if there truly is overheating or whether it is a gauge issue. Assuming it is overheating...I'd look first at the above items. Why do you have the high side switch jumpered?

 

I was actually going to go today and get a IR thermometer to see if it was truly overheating but I honestly think it is because when it starts doing that you can feel a temperature change in the cabin.

I did check the belts last night to make sure there were tensioned correctly. I also did a full flush a few months ago when I replaced the timing belt and water pump. I did check the coolant level this morning because I thought from the over heating I might be low but the level is the same as it has always been.

You mentioned the thermal fan clutch. Are you referring to the electric fan or the regular cooling fan clutch?

 

Sounds as if you have already eliminatedsome potential issues. The thermal fan clutch is the vaned center portion of the belt driven mechanical fan. The auxiliary condenser fan up front just helps to lower head pressure a little bit for the a/c. It doesn't move enough air to be much of a player in the cooling of the engine. The thermal fan clutch free wheels at highway speeds and locks in at lower speeds; if it has failed or is failing, it would produce the exact symptoms you describe.