Summer in East Texas Finds Every Weak Spot in Your Car. Here's the Checklist Before You Load Up.

Heat is the great revealer. The marginal battery that turned over fine all spring, the A/C that has been blowing just a little weaker than it used to, the tire running a few pounds low, the coolant that is a year past due. All spring they held together. Then the first real 100-degree week hits, you load up the family for the lake or the long drive to see relatives, and somewhere about an hour down the road every one of those weak spots decides to fail at once, on the shoulder, in the worst heat of the day.

Here is the part most people have exactly backwards, and it is worth saying first because it changes how you think about the whole season. Summer heat kills more car batteries than winter cold does. We see it every July. The roadside numbers back it up, with AAA reporting close to two million battery-related service calls every summer. So before you point the car down Highway 110 with everybody loaded in, run this list, or let us run it for you.

Battery: the surprising one

Everybody braces for the battery in January. Almost nobody thinks about it in July, and July is when it actually gives out.

The reason is chemistry. A car battery makes power through a chemical reaction, and heat speeds that reaction up while also accelerating the evaporation of the fluid inside the battery. Run those two effects together over a long hot summer and the battery wears out from the inside, faster than cold ever wears it out. Cold weather gets all the blame because winter is when a battery already weakened by the heat finally fails to crank on a frosty morning. But the damage was done months earlier, in July and August, sitting in a parking lot in the sun. The number tells the story plainly. A battery that might last 58 months or more in the far north of the country often gives up in under 41 months down here in the hot South. Our climate is simply harder on batteries, and a battery that is three or four years old going into a Texas summer is living on borrowed time.

What to do is simple. If your battery is three years old or more, have it load tested before any long trip. A load test is not the same as a quick voltage check. Voltage just tells you what is in the tank right now. A load test simulates the actual stress of starting the engine and tells you whether the battery can hold up under that pressure, which is the only thing you care about when you are two hours from home. While we are in there, we look for corrosion on the terminals, that bluish-white powder that builds up and chokes the connection, and we make sure the battery is clamped down tight, because heat plus engine vibration is the exact combination that finishes a marginal battery off early. The whole test takes a few minutes, and we do it free.

Cooling system: watch the gauge

Your engine makes a tremendous amount of heat all on its own, even on a mild day. Add an East Texas afternoon and a low or tired cooling system, and the margin you have before things go wrong gets thin fast.

Extreme heat breaks coolant down over time and speeds up how fast you lose it, so the level you topped off last fall may not be the level you have now. Check the coolant level at the overflow reservoir when the engine is completely cold, and never, ever open a hot cooling system, because a hot system is pressurized and will spray scalding coolant the moment the cap turns. While you are looking, notice whether the coolant looks clean and bright or rusty, brown, and tired, because old coolant loses its ability to move heat and to protect the metal inside your engine.

Your temperature gauge is the early-warning system here, and most people ignore it until it is too late. Learn where the needle normally sits once the engine is warmed up. That spot is your baseline. If it starts creeping higher than that baseline, especially in stop-and-go traffic or while towing or climbing a grade, that is the car telling you, calmly, to get off the road before it tells you the expensive way with steam from under the hood. An overheated engine is one of the few car problems that can go from inconvenient to a cracked head or a blown head gasket in a matter of minutes. Coolant flushes are part of normal routine maintenance, and getting one before the season starts beats discovering you needed one on the side of the interstate.

A/C: "blowing warm" is rarely "just add freon"

This is the one that turns into a thousand-dollar surprise when people ignore it, so deal with it before the trip, not during it.

When the air starts blowing warm, the instinct is to assume it just needs a recharge, a quick top-off of refrigerant, and to grab a can off the shelf at the parts store. Sometimes a recharge really is all it needs. But here is the part the can does not mention. An A/C system is sealed. It is supposed to hold the same refrigerant for years. A sealed system that has lost enough refrigerant to blow warm has lost it because there is a leak somewhere, and pouring more refrigerant in does not fix a leak. It just buys you a few weeks until the new refrigerant escapes the same way the old refrigerant did, and now you have spent money twice and still have warm air, plus refrigerant venting out into the atmosphere where it does not belong.

The honest version is that warm air can be a simple low charge, a leak at a fitting or a hose, a failing compressor, an electrical fault, a stuck blend door, or a couple of other things, and the only way to know which one you have is to actually diagnose it. We find the leak, we fix the cause, and then we charge the system to the right level so it stays cold. Get the A/C looked at before you are depending on it across three hot hours with kids in the back seat asking how much longer.

Tires: heat finds the weak one

Hot pavement and a tire are not friends, and the friendship gets worse if the tire is already low or already worn.

Heat raises the air pressure inside your tires, and it concentrates the most stress on the tires that are already underinflated or worn thin, because a low or worn tire flexes more, and flexing builds heat, and heat plus a weak spot is what turns a marginal tire into a blowout at highway speed. Check your tire pressures when the tires are cold, meaning before you have driven on them or after they have sat a few hours, and check them against the number on the sticker inside your driver's door jamb, not the larger number molded into the tire's sidewall. That sidewall number is the tire's maximum, not your car's target, and inflating to it is a common mistake. Look at the tread depth and look for uneven wear across the tire, because uneven wear often points to an alignment or suspension issue worth catching now rather than discovering through a tire that wore out months early. And check that your spare is actually up to pressure, because the day you find out your spare is flat is always the day you needed it.

Fluids and brakes, before you hitch up

Two more before you go, and they take almost no time.

Heat accelerates the loss of every fluid in the car, not just coolant, so this is a good moment to have the oil, transmission fluid, brake fluid, and power steering fluid looked over together as a set rather than one at a time. Low or burnt fluid under summer load is how small problems quietly become roadside problems.

And if your trip involves towing a trailer or a boat, or any real grades, your brakes are about to be asked to do considerably more than they do on your daily run to the grocery store. A fully loaded vehicle on a long downhill grade is the exact situation where tired brakes finally show themselves, usually at the worst possible point on the hill. If you have noticed any of the warning lights we covered in our brake guide, a squeal, a soft pedal, or an ABS light, get that sorted before you hitch up, not after.

The twenty-minute version

You do not have to do all of this yourself in your driveway with the owner's manual open on the fender. The entire point of a pre-trip check is that twenty minutes now prevents the afternoon stranded near Bullard with the whole family and a car that will not move. Battery load test, coolant level and condition, A/C, tire pressures checked cold, a fluid look-over, and a brake check is the complete list. It is the same list we would run on our own vehicles before our own families climbed in, and there is nothing on it that needs to wait until something has already gone wrong.