A guide to getting your car ready for summer heat, covering cooling system checks, AC service, tire adjustments, and heat-related wear prevention to avoid breakdowns in high temperatures.
Last updated:
0 of 20 completed0%
Copied!
Cooling System
Check coolant level and top off or flush if due
Coolant should be changed every 30,000-50,000 miles or every 5 years. A flush costs $100-150. Low coolant in summer heat leads to overheating, which can warp a cylinder head — a $1,500-3,000 repair.
Inspect radiator hoses for cracks, bulges, or soft spots
Radiator hoses deteriorate from the inside out due to heat. Squeeze the upper and lower hoses when cold — they should feel firm but pliable. A hose replacement costs $50-150; a burst hose on the highway costs a tow plus engine damage.
Verify the radiator fan operates when the engine reaches operating temperature
Let the car idle for 10-15 minutes until the temperature gauge reaches normal. The electric fan should kick on. If it doesn't, you'll overheat in stop-and-go traffic. Fan motor replacement costs $200-500.
Check the thermostat for proper operation
A stuck thermostat causes overheating or prevents the engine from reaching operating temperature. If your temp gauge runs high in traffic but normalizes on the highway, the thermostat may be sticking. Replacement costs $150-300.
Air Conditioning Service
Test AC output with a thermometer in the center vent
A properly functioning AC should blow air at 38-45°F from the center vent on max cold after 5 minutes. If it's above 50°F, the system likely needs a recharge or has a leak.
Have the AC system recharged if cooling is weak
A professional AC recharge costs $150-300 and includes a leak check. DIY recharge kits cost $30-50 but don't test for leaks. If the system needs recharging every year, you have a leak that costs $200-800 to fix.
Replace the cabin air filter for maximum airflow
A clogged cabin filter reduces AC output by 20-30% and makes the system work harder. Replacement costs $15-25 for the filter and takes 10 minutes. If it smells musty when you first turn on the AC, the filter is overdue.
Inspect the AC condenser for debris and clean if blocked
The condenser sits in front of the radiator and collects bugs, leaves, and road debris. A blocked condenser reduces AC efficiency by 15-25%. You can gently rinse it with a garden hose from the engine side — never use a pressure washer.
Tires and Brakes
Switch from winter tires back to all-season or summer tires
Winter tire rubber compound starts to degrade rapidly above 50°F, wearing 30-40% faster in summer heat. Summer tires handle better and last longer in warm weather. Swap when average daily temps stay above 50°F.
For every 10°F increase in temperature, tires gain about 1 PSI. Overinflated tires wear faster in the center and have less grip. Always check pressure in the morning before driving, when tires are coolest.
Inspect tires for dry rot, sidewall cracks, and bulges
Heat accelerates rubber degradation. Tires older than 6 years (check the DOT date code on the sidewall — 4 digits, e.g., 2220 = week 22 of 2020) should be replaced regardless of tread depth.
Inspect brake pads and fluid before hot-weather driving
Summer road trips and mountain driving put extra stress on brakes. Brake fluid boils at lower temperatures when contaminated with moisture, causing brake fade on long descents. A fluid test is free at most shops.
Fluids and Belts
Check and top off all fluids: oil, transmission, power steering, and brake
Heat thins all fluids and accelerates breakdown. If your oil change is due within 1,000 miles, do it now before summer driving. Low transmission fluid in high heat can cause the transmission to overheat and slip.
Inspect the serpentine belt for cracks, glazing, or fraying
Heat is the primary killer of serpentine belts. A belt that looks fine in winter can crack and fail in summer. Replacement costs $25-75 for the belt plus $50-100 in labor. A belt failure in 100°F heat leaves you stranded without AC or power steering.
Switch to summer-blend windshield washer fluid
Summer washer fluid ($3-5/gallon) contains bug-removing agents that winter fluid lacks. Road bugs bake onto windshields in minutes at highway speed and regular fluid won't cut through them.
Check the transmission temperature if your car has a gauge or warning light
Transmission fluid should stay below 200°F under normal conditions. Towing, mountain driving, or stop-and-go traffic in heat can push temps to 250°F+. An auxiliary transmission cooler costs $50-150 and prevents overheating damage.
Interior and Exterior Protection
Install or replace a windshield sun shade
A parked car's interior can reach 140-170°F in direct sun. A reflective windshield shade reduces interior temperature by 30-40°F and costs $10-25. It also protects the dashboard from UV cracking.
Apply UV protectant to the dashboard, seats, and trim
UV rays cause leather seats to crack and plastic trim to fade within 2-3 years without protection. A UV protectant spray ($8-15) applied monthly creates a barrier. Leather conditioning costs $10-20 and prevents $500-1,500 in seat damage.
Wax or apply a sealant to the exterior paint
Summer sun, bird droppings, and tree sap damage unprotected paint within weeks. A quality wax application costs $15-30 in materials and lasts 2-3 months. A ceramic sealant costs $30-60 but lasts 6-12 months.
Check that all windows and sunroof seals are intact
Summer thunderstorms can dump heavy rain in minutes. Leaky window seals cause water damage to door panels and carpet. Run a garden hose along each window seal for 2 minutes and check inside for drips.
Frequently Asked Questions
How hot is too hot for a car engine in summer?
Normal engine operating temperature ranges from 195 to 220 degrees Fahrenheit. The temperature gauge entering the red zone or a reading above 230 degrees Fahrenheit signals overheating. Pull over and shut off the engine within 60 seconds of the warning light to prevent head gasket failure or engine block warping, both of which cost $2,000-$5,000 to repair. Running the heater at full blast can buy a few extra minutes by pulling heat away from the engine, enough time to reach a safe stopping point.
Does hot weather affect tire pressure?
Tire pressure increases approximately 1 PSI for every 10-degree Fahrenheit rise in ambient temperature. On a 100-degree summer day, tires that were set to 35 PSI in a 60-degree garage may read 39 PSI on hot pavement. Overinflated tires wear faster in the center of the tread and have a smaller contact patch, reducing grip. Check tire pressure in the morning before driving when tires are cool, and set them to the number on the driver door sticker, not the maximum printed on the tire sidewall.
How often should car AC be recharged?
A properly sealed AC system should never need recharging. If your AC blows warm, the system has a leak that needs repair before adding refrigerant. DIY recharge kits ($30-$50) mask the problem temporarily and often overcharge the system, damaging the compressor ($500-$1,200 to replace). A professional AC diagnostic and leak test costs $100-$150, and a full repair with new refrigerant runs $200-$400. Most AC failures trace back to a leaking O-ring or condenser, both of which are relatively inexpensive parts.
Can extreme heat damage car paint?
Sustained UV exposure degrades clear coat at a rate visible within 2-3 years on unprotected vehicles. Paint surface temperatures on dark-colored cars can exceed 170 degrees Fahrenheit in direct sun, accelerating oxidation and fading. Parking in shade, using a windshield sun shade ($15-$25), and applying a ceramic coating or quality wax every 3-6 months blocks 90%+ of UV damage. A professional paint correction to fix sun-damaged clear coat costs $500-$1,500 depending on severity.
What coolant ratio should I use in summer?
A 50/50 mix of antifreeze and distilled water is the standard year-round recommendation for most vehicles. Pure antifreeze actually transfers heat less efficiently than the mixed solution and can cause overheating. The 50/50 blend protects against freezing down to -34 degrees Fahrenheit and boiling up to 265 degrees Fahrenheit under pressure. In extreme desert climates above 115 degrees Fahrenheit, some manufacturers approve a 40/60 antifreeze-to-water ratio for slightly better heat transfer. Always use distilled water, not tap water, since mineral deposits from tap water corrode internal cooling passages.