I have searched the forum but seem to have the opposite problem that everyone else has with overheating. My truck stays cool at idle and cruising around town and stays around 195. However with these hot days 85+ when driving on the highway for extended time with the ac on the temp goes above 230 and the needle rises until I pull over and let the fan cool off the car.

Any suggestions as to the culprit?

 

Had the same problem on another car, it was a bad thermostat.

 

This is just a guess:
Looking at your sig line your JK is probably quite heavy even for a JK. When you combine that with the aerodynamics of a brick it takes alot of power to keep you moving at high speeds. On top of that you have a supercharger which lets the 3.8 make even more power than it was ever designed to make.

So my guess is that weight + bad aerodynamics + supercharger makes A LOT of heat at highway speeds. on the other hand the motor is not working very hard to put around town at 30-40 MPH.

I would look into a larger radiator, like the ones they use for Hemi conversions.

 

All that, and, do you have an intercooler in front of the radiator?

What else do you have piled on the bumper, in front of the grill?

It all takes away from cooling system's ability to take heat from the water at higher power settings.

 

Yup I did not even think of those.

My naturally aspirated JK has trouble maintaining speeds above 70 mph at sea level on flat land. It really feels like I am pushing it to maintain a faster speed and I do not have dana 60's or full skid plates weighing me down. If I added a supercharger the extra HP would make it feel better at higher speeds but the engine its-self is still feeling much much more strain at 75 than 70 and even more if you are trying 80. And Strain = Heat.

 

What he said. In the meantime put the air dam back on and see if that helps.

 

Thank you all

I do have a intercooler in front as well as a warn power plant but the winch does sit very low in the bumper and does not block the grill. I am surprised that I am having the overheating as I added the griffin radiator last year and ran this same set up without any problems but this year something has changed.

The other odd thing is that when I really push the motor with hard accelerations and high rpms it does not over heat. It is more at the 2200 rpm constant load on the highway which leaves me around 70 MPH

 

Try adding some additive called water wetter to the rad I used it in my street rod and it dropped the temp by 20 deg. The air dam is there for a reason it helps direct air into the rad at highway speeds that's why every car has one it also smooths out the airflow under the vehicle witch gives you better gas mileage.

 

You are ok at idle, which means the fan comes on, pulling air through the radiator. This also indicates the temp sensor and thermostat are ok.

The problem has to be turbulent air flow, or insufficient air flow, through the radiator, at speed.

All the things you have going on in front of the radiator contribute to that.
Removing the air dam raises the pressure in the engine bay; also a contributing factor.

Is there any chance you have some mud/debris in the radiator fins?

 

Thank you again for your help. I have no mud in the fins. so it must be air flow. I have two questions through. First, does having the aev hood etc help with the pressure problem you suggested or should I go back to the stock hood. Second, if I take the intercooler out and there is nothing infront and the problem still exists what solutions are there?