It's a Dry Heat: How Ford Tests the F-150 in the Arizona Desert

• What's new: Ford invited me to see how it tests the effects of hot weather on its products, including the 2027 F-150 pickup.
• Why it matters: Air conditioning and engine cooling have to work on even the hottest days.
• Edmunds says: Ford uses some clever tricks to put a real strain on its test vehicles. 

Sensors and sensibility

While this looks like a 2025 F-150 — in fact, the body shell was produced in 2025 — it's a prototype for the recently refreshed 2027 model. Ford wouldn't tell us what new equipment the truck was outfitted with to test, but it had something to do with making sure things don't get too hot, and engineers use the same basic methods regardless of what's being tortured. Even small changes like those for the 2027 model have to be validated to make sure the new setup won't roast its complex power electronics, battery, or anything else under the truck.

That's where the thermocouples come in — about 500 of them on this F-150. A thermocouple is a relatively simple sensing device that places two dissimilar metals in an area to be tested and produces a temperature-dependent voltage. That voltage travels through the spaghetti of yellow wires and is translated into a temperature reading in the engineer's computer.

On our hybrid test subject, they're tacked onto things you'd expect to get hot — exhaust manifolds, catalytic converters, heat exchangers — as well as items you might not think of as being in the line of fire, such as the undermount spare tire. (I counted two probes embedded into the rubber alone.) All of these sensors give engineers a picture of where the heat is heading in and around the vehicle, enabling the stress testing done at the Arizona Proving Ground and on real roads in the southwest.

Then there are the dots. The silver spots you see all over the F-150 are not a new graphics package, but an aid in turning this physical machine into a digital 3D object. The dots are used to capture the vehicle's shape, which then gets used to model airflow around it, which in turn is correlated to the temperature readings captured from the thermocouples.

Other sensors include fiber-optic "eyes" that measure fan speeds and tubes to monitor stagnation and air pressure. For things that rotate or move, like driveshafts and suspension elements, they use infrared thermocouples. The prep even goes as far as draining fuel from the test vehicle's tank and replacing it with fuel that's a set temperature. Batteries go into an oven to be baked to thermal perfection before being dropped in for a test. Repeatability is important in these kinds of evaluations.

Bringing the Davis Dam to the Phoenix area

Ford's Arizona Proving Ground is located about an hour outside Phoenix. It's plenty hot there, of course, but it's also pretty flat. Serious grades challenge any powertrain, and there are few more serious than the Davis Dam Grade, a stretch of Arizona State Route 68 that's the basis for an SAE towing standard (J2807). At its steepest, the road to the top of the dam has a 12% grade, or a little less than 7 degrees. That may not sound like much, but for reference, federal regulations say the steepest incline you'll see on an interstate is 7%.

Instead of making the three-hour drive northwest to the actual dam site in Kingman, Arizona, all the time, the test team can simulate the conditions right at APG. The key is something called a trailer dyno.

This is an actual trailer, hitched to the back of a vehicle like any other, but it doesn't weigh tons. Instead, it uses an electric motor to apply load, simulating weight, grade or both. The red one behind this F-150 uses a gas engine to power the electric motor, while others are all-electric; it can be dialed up to reproduce the effect of up to 25,000 pounds. Pretty neat.

I got to ride in an Explorer Tremor undergoing its own hot-weather torture. Before attaching a smaller trailer dyno good for up to 15,000 simulated pounds, I took a few laps of the banked oval to get everything up to operating temperature. With the dyno hooked up, and controlled from within the vehicle, I sat shotgun at a computer with tons of constantly changing numbers. The view I saw showed a list of the many thermocouples and their readings, as well as a graph of how hard the engine was working.

For some reason the engineers trusted me to click on a field in the testing software and enter a new number. I replaced 100 with 72 and immediately felt the SUV slow down to a new governed speed of — you guessed it — 72 kph. Adjusting parameters like this allows them to more precisely control the test, lapping with foot to the floor and knowing the vehicle won't exceed the test parameters. I considered setting it to the max of 400 when no one was looking but thought better of it.

After lapping the oval under load and getting everything nice and hot, the engineers park the test vehicle in a heat soak "shed." These walled structures have a gate at either end and no roof to keep the solar load coming. The engine stays running while the heat it gives off mingles with the ambient conditions and bakes it all. It's meant to mimic pulling into a garage after stressing the vehicle — the proverbial riding hard and putting away wet — which is about the worst thing you can do to a vehicle, at least thermally. Temps get to their hottest within two to five minutes. During this testing, they're not just looking at heat outside the vehicle, but making sure the A/C system can keep up with demand. For what it's worth, I was plenty comfortable inside.

Hug an engineer

I asked the engineers if they have a color preference or get any say in the paint that comes on their test vehicles. I'm paraphrasing, but the response was basically if the color of the paint makes the difference in heat load, there's something very wrong somewhere. In other words, there is some effect based on the body color — darker colors absorb more heat — but it's small enough that they can get a confident result even with a white test vehicle. As it happens, the most common colors they see are white and black, with white common because that's usually the color of initial prototypes.

Not that I needed numerical proof that it was roasting outside, but I took one more look at the temp display on my way out of the office; it was up to 108.3 degrees. So the next time you're abusing your vehicle in hot weather and staying nice and cool inside, give thanks to the engineers who spend their summers in Arizona to make it possible.