Cover Story: Another Day in Paradise

Severe weather fleet: surviving 125 degree temperatures.

“You can’t have failures in the emergency vehicle industry, so what you do is, you start PM programs prior to failures,” O’Brien explains. “So, we started seeing starters would last about 120,000 miles. Alternators, we were getting about 60,000 miles before failure.

“But, some of our early alternator failures were due to people not following procedures,” he admits. “If you put all your emergency lights on, you’re looking at a very high amperage drop. The older lighting systems might draw anywhere from 150 to 200 amps. You add a 1,000 watt converter and you’re drawing another 100 amps off. Well, with a two alternator system you’ve maxed out at 230 amps-times-two system. With 400 plus degrees under the hood in the summertime, you cannot charge your batteries. So we implemented a system: we had our idlers set at 1,500 to 1,750 rpm. This gave us the maximum output on our fan systems drawing air through the radiator, which gave us the most cooling we could have.”


Sometimes beating the heat calls for creative thinking. Such a case came up when underhood temperatures in O’Brien’s Ford E-Series ambulances started causing serious electrical problems.

“We had to put complete new looms in them because we were literally baking and melting the wires together inside the looms,” O’Brien says. “When you start melting and compromising the wiring, you start to get engine shorts and electronic failures on your mission components. We were wrapping all the engine looms on the E-Series in asbestos, then we had to put metal clamps around them to keep the asbestos on them, and that was the only way we kept the harnesses from burning.”

O’Brien’s creative solution? If you can’t change the truck, change trucks. He replaced his E-Series Fords with F-Series trucks, in order to get more underhood space and more cooling under the hood.

“We still see temperatures up at 300 to 350 degrees with the F-Series, but that’s a far cry from 425 degrees melting plastic underneath an E-Series,” he says.

Charging batteries in extreme heat calls for even greater creativity.

“Now, obviously we don’t get very good battery life if the batteries are under the hood at 400 degrees,” O’Brien says, “because all that electrolyte is sitting there boiling and it’s constantly gassing. You put blankets around them and it doesn’t do any good; it just saturates those blankets with acid and then you end up with corrosion under the hood, issues with battery cables and connections.”

O’Brien’s solution is to compartmentalize batteries away from the engine and heat sources. Many of his vehicles have batteries in extra locations: they might be behind the driver or passenger, or they might be under the vehicle on the frame out.

“Underneath the vehicle is not going to be a good choice, especially if you have to sit there idling the vehicle,” he says. “We don’t have a choice. Our trucks are going to be idling—we can’t shut them off.

“All of our vehicles have battery chargers on them with shore lines. When our vehicles leave their batteries are fully charged with a variable-voltage charger-conditioner that sits there and doesn’t make a battery with a memory. Yeah, you’re going to spend a lot of money on a charger-conditioner, but the reliability of your vehicle and your battery life depends on it.”


After many years of keeping vehicles running in the Nevada desert, O’Brien seems to have developed a strong survival instinct. If there’s a vehicle system that’s adversely affected by heat, he’s figured out an adaptation.

Remember that diurnal temperature shift of 90 degrees in a 24-hour period? Well, guess what that can do to tires. Tire air pressure can change dramatically from night to day, wreaking havoc with tire life and ride quality.

O’Brien’s solution? If you can’t change the air, change the gas.

“Nitrogen-filled tires—my God, why didn’t we start looking at that years ago?” he exclaims.

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