Is it okay to run the air conditioning without turning off the engine?

[IanRose]

It is acceptable to run the air conditioning without turning off the engine for a short period. However, doing so for an extended time can cause damage to the vehicle. The hazards of running the air conditioning without turning off the engine are as follows: Toxic gases entering the car: Prolonged idling of the car can produce toxic gases, which may enter the vehicle through the air conditioning system and pose a risk of poisoning. Damage to the engine: Failing to turn off the air conditioning before shutting down the engine can cause the vehicle to start with the air conditioning compressor engaged the next time it is turned on. This increases the load on the engine and, over time, can cause some damage to the engine. Battery drain: When the car is turned off, the air conditioning will start consuming power from the battery. Over time, this may lead to battery drain.

[DelLouis]

Yes, you can temporarily run the AC without turning off the engine. I often do this when picking up my kids from school. However, prolonged idling with the AC on can cause carbon buildup in the engine. My old mechanic friend says it's like making someone work hard while panting in place. In summer, 15 minutes of cooling is enough for the car interior. I usually keep the windows open for ventilation and turn off the AC once it's cool. If you smell gasoline or see blue smoke from the exhaust pipe, turn off the engine immediately and check it out. Don’t wait until the oxygen sensor burns out like my neighbor did—you’ll regret it.

[DiLouis]

I've done the math on fuel consumption: Running the AC in a sedan for about an hour burns roughly 2 liters of fuel—that's enough to buy a bottle of drink at a convenience store. A colleague once idled with the AC on for three hours in traffic, and the fuel gauge dropped a full notch. Worse yet is the battery—I once ran the car fridge and AC simultaneously, and the battery died in just three months. Now, I use a mobile app to remotely start the car and turn on the AC ten minutes before getting in, saving fuel and protecting the vehicle. Just remember not to do this in an enclosed garage—carbon monoxide poisoning is no joke.

[McLeo]

The 30-second cooling method really works for me: first, blast the air at maximum for half a minute to expel the hot air, then turn on the AC. A mechanic taught me this trick, saying it saves the engine compared to turning on the AC directly. On hot days when I take the kids out, I remotely start the car in advance, so when we get in, it feels like stepping into a fridge. However, I turn off the engine for a break if it's been running for over 20 minutes. Last year, I saw a taxi driver who kept the AC on for three hours straight, and the radiator ended up boiling over.

[TaliaLee]

That accident in my underground garage really scared me: my neighbor was sleeping in the closed garage with the air conditioning on. Fortunately, the property management smelled the exhaust fumes and broke in to save them. Now whenever I see someone idling with the air conditioning on in the garage, I go knock on their window to remind them. Truck driver Lao Wang said their fleet has a rule that engines must be turned off if idling exceeds 15 minutes. The police have even posted warning notices, stating that idling emissions are ten times more polluting than driving. If you need to cool off, it's better to find some shade and crack the windows for ventilation—it's much safer.

[JosiahRose]

Two years ago, my old Jeep suffered a setback: idling with the AC on for two consecutive days at the campsite left the battery completely dead on the third day. A professional diagnosis revealed aggravated wear on the DC motor, and replacing the battery cost over a thousand yuan. Now, when going on road trips with my family, I bring foldable sunshades and a USB mini fan that can run all night on a power bank. If I need to use the AC, I limit it to half an hour at most, then start the car and take a short drive to let the engine stretch its legs.