That is why they made electric fans, usually the only time the vehicle needs the fan to create airflow through the radiators is when it is sitting still at idle. There are a few other times. But with an electric fan, it turns off when NOT needed and spares the engine the drag of running an unneeded fan. Of course it has to turn back on again when needed.
So, from you description it really sounds like the fan is NOT coming on.
Pressure cap is another possibility, fan the biggest, if its NOT sealing and holding the pressure on the system, you'll get boil over and the engine will overheat as it boils over.
Water pump, the least, but possible, usually a bad water pump causes leaks and hot while traveling at high way speeds, but its possible for the impeller to erode away from cavitation (especially if the anti-freeze was long overdue for changing) and that would hurt performance all around.
So you changed the coolant, did you use the correct coolant? Chrysler HOAT anti-freeze either from the Dealer or the only aftermarket equivalent, Zerex G-05? Most of the anti-freezes sold on store shelfs, that vaguely allude to being universal, are far from it, they are a form of Dexcool or another OAT type anti-freeze, they do NOT mix with OEM type of anti-freeze (despite what they say on the jug) and Chrysler specifically recommends NOT to use OAT anti-freezes in the Commander.
BTW, the AC needs airflow over the condenser, if it doesn't get it, its cooling performance will suffer greatly, and eventually it will shutdown when the condensing pressures get to high from the lack of cooling at the condenser. Also keep in mind, when the engine is running hot, the AC condenser is dumping heat into the engine cooling radiator making it even hotter. The first thing you should always do when your engine is getting hot, is too turn off the AC, 2nd would be to open the windows and run the heater on high to help cool the motor.
When the motor overheats, for some reason the PCM/TCM will also calculate the trans temp off the engine temp and set a code for trans overheat/temp. Seen it happen lots of times in modern Jeeps. Once the motor cools off, everything goes back to normal.
Last edited by Mongo; 06-12-2015 at 03:00 PM.