Jldude84

So most of this truck's life (2015 5.0L XLT) has been in Florida. It's seen several full summers there. Temps there regularly hover around 95 degrees and ~75% humidity and I've never noticed this. However, as soon as I moved to southern Arizona, and the outside daytime temps crept up over 100 degrees, I noticed the cooling fans seem to come on a LOT. Which I would understand if I'd been sitting in traffic at 110+ degrees, but if the A/C is on, the fans will turn on immediately as soon as you start the truck, even if it's "cold" and hasn't run for days. I experimented a bit and started it cold with no A/C on, no fans, quiet as can be. Totally normal. My coolant was indeed a tad low, but even after topping off, it still behaves the same. However I do find that the fan does EVENTUALLY turn off (or at least to low speed where I can't hear it when stopped at a light), but it takes a long time. I think I'm gonna drive up the mountain to where it's much cooler and let it sit and then start it with AC on to see if it is indeed just an outdoor ambient temperature thing.

Anyone else from desert regions experience this in their truck? I've read that the expansion valve can be a culprit causing a false computer reading and causing the fan to blow constantly, but I'm hoping this isn't the cause.

Update: So this evening it got down below 95 degrees, and after the sun went down, I drove to the store, and tried multiple times and couldn't duplicate this behavior, I turn the AC on and the fan didn't seem to turn on, or if it did it certainly wasn't blasting loud like it usually does. So maybe it is indeed normal when it's over 100 outside? Still gonna take it up the mountain where it's cooler and test it again though to be sure.

Critical Mass

I had the expansion valve fail on my 2011 5.0. It had the same symptoms as yours. The fans would be screaming all the time even in cooler temperatures, only when the AC was on. It wasn't a huge bill to replace it. I think it was about $300.

I think the high fan speeds may also indicate low refrigerant.

RL1990

I would assume the truck is working perfectly normal, you didn't mention any problems cooling down the cabin. The PCM takes data from multiple sensors to determine A/C operation. When it's 110 outside, even on a cold start, the truck is going to crank the fans up to high speed to get the A/C as cold as possible to absorb as much heat from the cabin as it can. The fans have to pull air through the condenser to get rid of that heat and also lower system pressure. But in these conditions the "cool" outside air is over 110 degrees so the fans have to run at high speed to dissipate as much heat from the condenser as it can. You will also notice that the compressor is not cycling in these conditions, it will run constantly because it's so hot the evaporator can't get cold enough to cycle off. In 100+ temperatures you should expect the cooling fans to run on high speed most of the time. It's not just your truck, stand in a parking lot as cars and trucks drive by and all of them will have cooling fans screaming.

You wouldn't want to go back to the old days of the engine driven clutch fan sitting in traffic on those hot days.