Truck overheats when A/C is turned on.

You can NOT read quality of antifreeze/coolant by lookong at it. Have it tested at a local parts store. Better yet just flush it if in question. As far as a/c on you need to check for air bubbles in the cooling as well as the clutch fan. If the fan spins too freely it won't cool. Check also and make sure the fins on the radiator aren't bent or clogged.

Use a garden hose and nozzle to clean radiator and condenser coil fins if partially clogged with dirt and bugs will cause your problem.

Sounds like u don't have enough cooling or ur ac compressor might be dragging due to bad bearing putting excess load on engine. Check water flow in radiator after it reached operating temperature to see if thermostat opens and water pump is pumping

I have a 2008 F150 4.2 when i turn on A/C truck over heat I change the clutch fan I change the thermostat and it's still overheating my second opportunity is to change radiator and possibly water pump even though there is no leakage from the water pump