If it's getting to 212F and your fans not coming on OR your AC fan not coming on when you use AC you have a defective AC FAN and thats making your temps go up more ..

 

Further, if the condenser fan is frozen this will cause air flow restrictions over the radiator which will impact temps, from 5 to 10 degrees in some conditions, at lower speeds.

To address the general overheating issues on the Discos; whether it be restricted air flow or restricted fluid (thermostat, clogged radiator), invest in a thermal imaging camera or have a shop scan your radiator system with one. It will instantly tell you where the hot spots are which will help you determine the root cause of the overhearing. Best $300 investment you can make in my opinion.

 

Hell yeah I like your style.

 

Fans are coming on with AC / at 212

 

Yeah thats true. Like I said this isn't a common occurrence. Been daily driving around down and temps are like 180-184. It has to be a flow restriction or just underpowered radiator at high speed up hills in hot temps.

We are going to have a heat wave this weekend and I will be able to test with no grill / third gear like was recommended and go from there. If I can get it down to 210 on the rare super hot day that I need to drive up a mountain, I will call that good and stop fiddling.

Thanks for the comments.

 

Okay...again...check your viscous fan. The electric fan mounted in front, is primarily for asisting airflow while A/C is on or during idle time in stop and go traffic...it basically does absolutely nothing at road speed. This is the job of the viscous fan, when it senses temperatures increasing...from the air exiting the radiator...the viscous clutch mechanism engages and draws/pulls more air across radiator.

Again, if it reaches undesireable temps during your next outing in the mountains...down shift trans into the next lower gear...if that doesn't make a difference after a brief driving period...pull over, stop engine, open hood and check viscous fan for resistance...should be substantial. If not...replace. lf it does have resistance...then you know you have another issue. Which, since radiator is new...this would leave us with the water pump, collapsing hose (possibly caused by a bad reservoir cap) or some other type of restriction.

My 04 was running warmer than intended, changed viscous fan...end of story.