Does starting a car with the air conditioning on damage the vehicle?

[EverlyRose]

Starting a car with the air conditioning on can potentially damage the vehicle. Here are the reasons: 1. At the moment of engine startup, most cars have an automatic power-off mechanism for electrical appliances. However, if the air conditioning compressor is immediately engaged after startup and set to MAX mode, it can still impose a significant load on the battery. 2. There is a recommended method for using the air conditioning: before reaching your destination with the air conditioning on, it is advisable to turn off the air conditioning in advance and continue blowing air to dry out the air conditioning system. This practice helps to dry the interior of the air conditioning system each time it is used, reducing the likelihood of moisture buildup and minimizing the occurrence of unpleasant odors.

[LaKai]

I used to always turn on the air conditioning right after starting the car, especially in summer, thinking it was convenient. But later, a mechanic pointed out that this habit actually harms the car. During a cold start, the engine is busy with self-checks and the oil lubrication system isn't fully operational yet. Turning on the AC adds extra load—the AC compressor kicks in suddenly, increasing engine strain. Older cars might shake violently, and the starter motor consumes more power. Even in newer cars, the start-stop system could malfunction. I tried turning off the AC before ignition, and the engine ran noticeably smoother and quieter. Honestly, waiting just a minute until the coolant temperature gauge moves before turning on the AC is gentler on the battery, belts, and even the AC pump—especially for cars over five years old. It's worth being cautious.

[LaErin]

From the perspective of engine control logic, the most critical issue with starting the engine with AC on is load imbalance. When the fuel pump is busy building oil pressure, the sudden engagement of the compressor can catch the ECU off guard, leading to either delayed air-fuel mixture adjustment causing carbon buildup or erratic idle speeds like a rollercoaster. Even worse, with coolant not yet circulating, the AC refrigerant becomes like sticky syrup clogging the pipes, making the compressor piston force its way and potentially scoring the cylinder walls. My hybrid once foolishly did this, triggering fault codes in the energy recovery system. However, many new cars now have delayed start protection, but owners of older vehicles should develop the instinct to turn off the AC knob before ignition. Waiting a dozen seconds after ignition before turning on the AC is truly caring for your car.

[SanRowan]

If you keep turning on the AC while starting the engine every day, the first victim will be the AC compressor—that screeching metal-on-metal sound at startup is its cry of agony. Running the compressor bearings dry without proper lubrication will wear them out in three to five years, and the repair bill could buy you a new smartphone. The condenser might also go on a chemical strike due to sudden pressure changes—I’ve seen cars spewing ice chips from the vents. Last time I watched a mechanic disassemble one at the dealership, the clutch plates caked with sludge looked like sun-dried sponges. Want your AC to last longer? Turn off the AC button before shutting down the engine, and only press it after the next startup. Try it, and you’ll notice the car breathes more smoothly.

[OElliott]

The biggest pitfall of starting the car with the AC on is that it wastes money and damages the vehicle. A cold start already requires three times the normal current, and with the AC fan kicking in, the battery voltage can drop below 10 volts, accelerating the aging of lead plates due to sulfuric acid crystallization—replacing a battery costs at least 500 yuan. The engine is forced to rev higher to compensate for the load, and in stop-and-go city traffic, fuel consumption can increase by half a liter. I specifically used an OBD scanner to compare: cars started without AC had an instant fuel consumption of 2.1 liters, while with AC on, it shot up to 3.8 liters. It's recommended to open the windows for half a minute before starting the car in the morning, then wait for the tachometer to stabilize at 800 RPM before turning on the AC. This protects the engine and saves fuel.