Does idling with the AC on harm the car?

[BrielleLynn]

Idling with the AC on is not a problem, with the biggest impact being fuel consumption, followed by waste. 1. When driving with the AC on, the power output consumed by the AC only accounts for a very small part of the engine's idle energy. 2. When idling with the AC on, the engine not only drives the AC compressor but also needs to maintain the normal operation of the power steering and brake booster pumps. The latter two functions are completely unnecessary when parked, so keeping them running is simply a waste of power. Idling with the AC on while stationary can cause harm or even death to occupants if not careful, due to: 1. At idle, even outdoors, if there is no wind, carbon monoxide can accumulate around the car, with the concentration increasing over time. 2. If the car is set to external air circulation, a large amount of carbon monoxide from outside could be drawn into the car, leading to carbon monoxide poisoning.

[DeSavannah]

I've been driving for over 30 years and have seen many cases of cars developing problems due to idling with the AC on. Short durations like a few minutes won't cause major issues, but if left idling for half an hour or longer, the engine runs at low RPM for extended periods while the compressor continuously draws power, which increases the load. Carbon buildup in the engine will accumulate, and over time, you may notice increased fuel consumption or noticeable vibrations. My neighbor's car once required expensive carbon cleaning during maintenance because of this. The AC system itself may also suffer from excessive wear, such as poor refrigerant circulation. My advice is to turn off the engine once the car cools down in hot summer weather—don't be lazy and keep it running. Regularly checking spark plugs and the intake system during maintenance can prevent these issues.

[BrookeRose]

From both economic and environmental perspectives, idling with the air conditioning on is indeed unwise. The engine consumes more fuel at idle, and turning on the AC wastes an additional 15% of fuel, equivalent to burning dozens of extra dollars per month. Coupled with increased emissions, it's harmful to the environment, and some cities have already banned idling. Prolonged idling under high engine load accelerates carbon buildup and shortens spark plug lifespan. I recommend limiting idling with the AC to under five minutes if necessary; opening windows for ventilation is more economical. Avoid using the AC in parking garages to prevent carbon monoxide buildup. Choosing the right time to use the AC makes your car more durable and saves money.

[Isaiah]

I think it's okay to occasionally idle a small car with the AC on, just don't make it a habit. It's fine to keep the AC running during brief stops, but if the engine idles for more than ten minutes, the continuous operation of the compressor increases the load and may lead to slight carbon buildup. In my first few years of driving, I often did this and later noticed a bit more shaking when starting up. Now I only use it briefly before turning it off or let it cool down before getting out of the car. The AC system needs regular maintenance, such as cleaning the condenser. In short, moderate use keeps the car healthy.

[ElliottRose]

The engine outputs less power at idle, and the air conditioning compressor requires engine power to drive the refrigerant cycle, increasing the load. This can lead to incomplete combustion, forming carbon deposits, and over time, spark plugs or oxygen sensors may be damaged. To avoid this, briefly turn on the air conditioning when parked, then turn it off or shut down the engine after five minutes. Additionally, the battery in start-stop vehicles may experience excessive discharge. Maintaining the engine at its optimal operating temperature is most efficient, and turning on the air conditioning a few minutes after starting the engine is more effective. Remember to check for engine carbon buildup every six months.

[DelQuinn]

Idling with the AC on carries risks but they are manageable. Short periods like waiting at traffic lights are fine, but prolonged stationary idling (e.g., waiting for someone or camping) accelerates carbon buildup and fuel consumption due to low engine RPM. Safety-wise, beware of carbon monoxide accumulation in underground parking. I never exceed 10 minutes - in summer I'd rather step out for fresh air. Long-term AC wear components like compressor or fan aging are potential hazards. Recommended maintenance includes throttle body cleaning per service intervals to ensure system efficiency.