Does using P gear with air conditioning on affect the car?

[VanKiara]

Leaving an automatic transmission car in P gear with the engine running and air conditioning on for a long time does not damage the car. P gear is the most common gear in automatic transmission models, usually located at the frontmost position of the gear shift console, in front of the R gear, designed to lock the axle when the car is stationary on a slope. However, when the vehicle is idling in place, the gasoline in the engine may not burn completely. If this happens frequently over a long period, it can increase the formation of carbon deposits in the engine, and relatively, fuel consumption may also increase. In addition, if you rest in the car with the air conditioning on in a confined environment, a large amount of gas can enter the car through the vehicle's ventilation system. Staying in the car for an extended period under such conditions can easily lead to carbon monoxide poisoning. If the driver must rest in the car, it is advisable to first park the car in an open and ventilated location. Then, lower the window by about two fingers' width for ventilation, and finally switch the air conditioning mode from internal circulation to external circulation to ensure proper air flow inside the car.

[DiHarley]

I often encounter car owners asking about this during repairs. Actually, there's no problem at all running the AC in P gear, as P gear is the parking gear and the transmission gears are locked. But you need to be careful not to do it for too long. Once, I had a client who waited in the basement with the AC on for an hour, and the battery ended up completely drained, leaving the car dead. The AC compressor is driven by the engine and really has nothing to do with the gear position. However, I recommend turning off the engine and opening the windows if it's going to be more than 20 minutes. It's quite common to run the AC for a short while while waiting in the summer. The key is to ensure the parking spot is well-ventilated and the engine doesn't overheat.

[ElizaLee]

Last week, my wife specifically asked her driving instructor about this, and the instructor said the P (Park) gear is designed for parking. It's so comfortable to wait in the car with the air conditioning on and music playing, but never do this in an enclosed garage! I once saw a news story on a short video about someone who almost had an accident after falling asleep with the AC on in an underground garage. Oh, and remember to check the coolant and fan. There was a time when my car's cooling fan got stuck, and the water temperature kept rising with the AC on. Actually, the key point isn't the gear, but whether the car can dissipate heat in time.

[Ribeiro]

Honestly, I've been driving for ride-hailing platforms for fifteen years, and I always shift to P gear and turn on the AC when waiting for orders at the airport. The key is to observe whether the idle speed remains stable. A freshly serviced car barely shakes, but if an older car starts rhythmically shaking with the AC on while stationary, you should immediately check the throttle body. Practical tests show that running the AC consumes about 0.8 liters more fuel per hour, which is much more economical than stop-and-go driving. Once, the engine warning light came on, and the repair shop diagnosed it as a carbon buildup issue. Now, I regularly add fuel system cleaner as part of my maintenance routine.

[OChase]

Friends with new energy vehicles don't have this worry, but petrol car owners should take note. When running the AC in P mode, touch the hood temperature - if it's scalding hot, it's dangerous. Especially for friends who've installed racing turbos - my cousin's modified car overheated last year due to a blocked radiator. On hot days when waiting with AC on, occasionally lightly press the accelerator to maintain 1500 RPM to assist water pump circulation. Veteran drivers know to set the AC to external circulation - this trick reduces engine load.

[OWeston]

Actually, the manufacturer's manual clearly states that idling with the A/C on in P mode is allowed, but it specifically notes that it should not exceed 30 minutes. Once, I got so engrossed in a TV series that I lost track of time, which triggered the engine overheating protection. Later, after installing an OBD scanner, I discovered that with the A/C on while parked in summer, the engine bay temperature could reach 85°C. Now, I've developed the habit of popping the hood to dissipate heat whenever waiting, and I even installed a solar-powered exhaust fan on the roof—fuel consumption instantly dropped by 0.2.