So this is just a suggestion, but if the alt fan is kicking on appropriately now, but you're still running hot (running cool when driving, running hot when stopped/idling), it's probably good to check your fan clutch. Chances are, if you've never replaced it, it's probably a good time to. It'll help keep things cooler when idling

 

Here is another item for you,you already have a toggle switch,just unplug your a/c comp,then when you need your electric fan just put your a/c on,the comp will not come on, but the electric fan will think it is and it will run.
I assume when you say it is shutting off you mean the fan not the motor,if you mean the fan,the problem is the switch,I forgot what year yours is,but if 90 and earlier,it is on the drivers side head against the firewall,91 and later it is on the thermostate housing.

 

if the trailer does not have brakes try putting on a set of trailer brakes and add a brake controller to the jeep. Makes a HUGE difference!

 

Its funny you should mention the switch on the thermostat. I went out for lunch. While it was cool I decided to check all connections and hoses for the 10th time just to be safe. . I unplugged the Coolant Temperature Sensor on the thermostat housing and plugged it back in, started the jeep, and now it runs like the ignition is retarded and the check engine light came on. But the odd thing is now it doesnt get hot and die.. Does this mean I had a bad CTS all along and the comp didn't recognize it till I unplugged it? Or did I just break something else

Thank you for the trailer brake idea. I might look into that after I get done dumping cash into the Jeepl

 

I will exsplain this the best I can,If your switch is bad or is the wrong one the comp will not come on when asked,nor will your fan come on as should,it also can have effect on engine performance because it is part of ecm calc,your fan and comp will not come on either if freon pressure is to low,your fan will come on if the pressure in the a/c system is ok,it does not care if the comp is on. I do not think you broke anything,just need to run down the issues. You can check your switch with an ohm meter and a pot of hot water,and thermometer,place switch in water,watch temp and when the switch shows resistance,check the temp to see where it is. You can just buy a new switch also. It does sound like the switch is bad or wrong one.
It can be hard to know exactly what is going on without a scanner,but I think you are on the right track.

 

Ran down and got a new Coolant Temperature Sensor threw it in and engine is still sluggish and check engine light is on. If I leave the sensor unplugged and start it, it sounds the same. I left the battery unhooked for a bit to try that (at this point I'm willing to try anything). I'm gonna put the new CPS I got in tonight and new thermostat then I guess I'll have to spend the $90 to pull some codes (stupid ODB I systems). At this point I'm stuck till I get those at least. Thanks for all the help guys, I've learned a ton about jeeps going through this so far.

 

Disconnect your battery terminals and touch them together for 30 to 40 seconds and your check engine light should go off. as far as the ignition, someone else will hopefully give some input on that.

 

Did you ever get anywhere with this? I think I am having the same problems.

 

I havn't gotten far because of money. But... I just threw in a 180 thermostat and so far it behaves as long as its not too hot outside. I'm trying to decide whether or not to get a new car or keep fighting this thing.

 

I'm having a similar yet different problem. Around town I'm usually fine but when on the interstate it will sometimes heat up. My fan cuts on when the AC is on but I have not seen it cut on while driving (obviously). Usually by the time I park it in the driveway the temp is back to 210 so I can never tell if its running or not.

Edit.. sorry about the old post.. forgot I did a search. Please close if needs be.