My temperature doesn't read right since I installed the Airgap (temperature sensor too short I guess). It reads just over the bottom mark in the normal range on the gauge instead of just under the 210º mark like it did when it was stock.
That being said, I know what the "normal" temperature" is for my gauge. I don't run the air conditioner because the temperature goes a little above normal when I do and I don't know what the actual temperature is.
I recently put on a new Four Seasons fan clutch and when I did I found what looked like an old fluid leak from the center of the stock unit.

The first 8 mile ride had the temperature where it should be with the air conditioner on. After that I moved the truck around a couple parking lots going to a few different stores and it started getting hot. It also got hot on the 14 mile ride after when the air conditioner was on.
I didn't run the air conditioner for a couple days and the temp was normal.
Last night I ran the air conditioner on the way home and the gauge was normal.
Should I chock this up to putting the new fan clutch through its paces?

 

I don't think there is any break-in period per se... But, having it loosen up a little in the first few hours of operation isn't beyond the realm of possibility. If things are lookin' like they work they way they should, I wouldn't worry about it.

 

I didn't have a problem with the airgap and temp readings but that fan clutch may be a bit aggressive, I had a fan clutch that did that. Except it was the opposite, ran to cold in the winter or to hot in the summer.

 

My assumption is that the thick fluid in the new clutch had to be warmed up and moved through the valve in there a couple times to break it in.

I have gotten the engine too cold for too long code a couple times since installing the airgap but the heat is good and hot so I chocked it up to the temp sensor reading wrong from not sticking into the coolant far enough. Since yours reads right that has me wanting to change the sensor to see if it'll read right.

 

I had a that happen before. When I did the plenum on my truck (before the airgap) my temp was reading lower than it should. I ended up putting a new sensor in and all was good.

 

id think a new fan clutch would over cool the engine if anything. A least until the the clutch breaks in, using the new heavy fluid logic.
Try replacing the sensor and making sure you have the cooling system properly bled. Air will cause all kinds of overheating issues.

 

Don't rule out water pump.

There's no reason these trucks should get hot driving in a parking lot. They are cold-natured beasts with that huge engine bay, huge radiator, and low t-stats (195 or 180 is lower than new cars). Mine takes forever to warm up in the winter (so I add a winter front) but it is always consistent. I also replaced a fan clutch recently to seek a vibration and nothing changed nor did I notice any break-in or anything. Also, the only time my fan runs is in the morning for the first half block. I have never overheated nor even gotten to 200 degrees. Ever. And I towed a fully loaded trailer on 285s over the mountains and into the south in August. Cold-natured beast!

If you're seeing hot temps, look at the cooling system: pump, hoses, coolant level, coolant age, heads cracked?, leaking radiator?, bad stat, etc.

 

sounds like your radiator is stopped up ! I can drive mine at 70mph pulling a trailer loaded with a car A/C on and it only runs at about 210-220 at the hottest

 

It seems fine now. One time yesterday it was hotter than usual after driving to town then being parked for a few minutes. It took a minute to cool off after starting it and driving. To and from work all weekend it was normal temp or slightly lower than normal.

I need to get a temperature probe or a new temperature sending unit so I can find out what the actual temperature is since my gauge has been reading low since the Airgap went on.