Truck starts getting hot when sitting still with the AC on. I put a new 2 row radiator in last week, replaced the water pump and put multiple fan clutches in as well. I've also changed out the thermostat housing for an aluminum one. When idling it will go up to 215-217 but I never hear the fan kick in and get loud like it used too. That's why I've tried multiple fan clutches but It still doesn't change anything.. they never seem to engage. Also I will note that I'm using the aftermarket sensors that came installed in the aluminum thermostat housing.. maybe the engine isn't really hot even though the gauge and obdII says it is. What am I missing here? Oh I've also verified with a heat gun the valve with the spring on the fan clutch does rotate when warmed up so I know the valve isn't stuck closed

 

Fan clutch is not electric, on its front is a bi-metal spring that is heated up by the center of the radiator, so radiator heat not engine heat is what engages the fan more
As the spring heats up it expands and then closes valves inside the "clutch part" causing the fan to spin closer and closer to water pump RPMs, increasing air flow

The Shroud is a very important part of fans cooling ability, so must be used, no shroud then no cooling when stopped

Before starting the engine after it has sat at least 6 hours, longer is better
Open the hood and spin the fan, it should be Cold Locked, hard to turn/spin
Start engine you should hear the cold lock blades grabbing lots of air, then after 5 seconds or so it should get quiet, shut off engine
Spin the fan now, should be easy to spin
If there was no Cold Lock then clutch is bad, period, even brand new

So you now know what locked and unlocked blades feel like

If temp gauge gets above 1/2(200degF) pull over and shut engine off, check the spin on the fan blade, should be locked
If not you may need to unbolt the shroud and move it back
Run your hand over radiator fins, should be nice even heat, hotter closer to upper rad hose, cooler closer to lower rad hose, but NO cold spots like in the center next to fan clutch spring
If there are cold spots then rad has clogged tubes, new or not

Coolant temp going up when stopped is almost always a bad fan clutch
Bad water pumps or clogged radiators will usually cause over all running warmer, definitely more when stopped, but would expect temp gauge at 1/2 most of the time, not below 1/2 which is normal

Temp gauge will go up above 1/2 if you are just warming up the engine and stopped, but just a couple of times, that's the thermostat opening and closing as the cold radiator coolant comes in and temp equalizes, that's normal, but usually won't be seen when driving

 

The thermostat was sticking closed.. while driving it jumped around from 192 to 199 never showed to overheat unless I was idling and the A/C was on. Now that thermostat has been replaced it stays cool of course and the temp is usually 190-192 while driving