Why Juan José says to open the windows for five seconds before using car air conditioning

Many of us have climbed into a car that’s been baking in a car park and immediately blasted the air conditioning straight at our faces. A Spanish mechanic went viral on social media after explaining why this everyday reflex can be a quiet mistake.

An almost automatic habit that could cost you

Juan José, a mechanic known for his car maintenance videos, highlighted something most drivers overlook during spells of intense heat. His advice is that you should switch on the air conditioning with the windows open for a few seconds before sealing the car up completely.

The reason is straightforward: a vehicle left in strong sunshine can reach over 60°C inside. At that temperature, plastics and dashboard trim can release substances that build up when the cabin is shut.

• Extreme heat: the inside of a car can climb past 60°C on bright, hot days, even if you’re only doing short journeys.
• Quick ventilation: dropping the windows for a few seconds lets the hottest air escape before you close everything up.
• Compounds from plastics: when cabin materials heat up, they can give off compounds that aren’t great to breathe in.
• Sign it’s working properly: water dripping under the car after using the air conditioning is a sign the system is healthy.
• Preventive check: before long trips, it’s worth confirming the air conditioning is cooling properly.

Five seconds that change the air inside the car

In practice, the most common misstep is to crank the air conditioning to full and shut all the windows immediately. That way, anyone inside ends up breathing the stagnant air that has been trapped for hours in the heat.

The fix is easy to build into your routine: start the air conditioning, keep the windows open for a few seconds, and only then close the car up. That short pause is enough to refresh the cabin air.

The detail that goes unnoticed under the sun

Heat trapped inside a closed car doesn’t only affect the people who get in afterwards. It can also damage items left on the seat or forgotten in the glovebox during the day.

It’s not just discomfort

What heat does to what’s left inside the car

Phones, tablets and power banks left in a vehicle can be harmed by extreme heat, losing performance or even warping.

Medicines are also affected by high temperatures and can lose some of their effectiveness if they stay inside the car for too long.

Because of that, alongside ventilating the cabin before using the air conditioning, it’s a good habit to remove anything heat-sensitive from the car as soon as your journey ends.

Your attention at the wheel depends on it too

Excessive heat in the cabin doesn’t just make you uncomfortable-it can also affect your mind. High in-car temperatures are associated with reduced reaction ability while driving.

A driver who responds more slowly in traffic is a genuine safety risk. So this air-conditioning habit isn’t only about comfort; it also becomes a matter of road safety.

Other care for the car in very hot weather

Before longer summer journeys, it’s also sensible to book a quick check, making sure the air conditioning is cooling well and that there are no signs of leaks in the system.

Ultimately, Juan José’s tip shows how small habits when you get into the car can make a difference. Ventilating before closing everything takes seconds, costs nothing, and helps protect the health of everyone travelling.

Found this tip useful? Share it with anyone who ends up getting into a hot car every day in summer.