Does Running Only the AC Without Driving Harm the Car?
3 Answers
Running only the air conditioning without driving the car can increase fuel consumption and exacerbate the formation and retention of engine carbon deposits. The correct way to use a car's air conditioning system is as follows: 1. Turn on the AC switch; 2. Adjust the air vent selector knob—direct the vents upward when using the cooling function and downward when using the heating function; 3. Adjust the fan speed switch; 4. Adjust the air recirculation mode selector knob; 5. Adjust the temperature control knob. Maintenance tips for the car's air conditioning system include: 1. Clean the air vents promptly; 2. Maintain the condenser regularly; 3. Clean or replace the cabin air filter in a timely manner. Recommended practices for efficient AC usage: 1. Turn off the AC when driving at low speeds; 2. Avoid smoking while the AC is on inside the car; 3. Turn off the engine before switching off the AC; 4. Activate recirculation mode immediately upon entering the car during summer.
With ten years of experience in car repair, I often encounter this issue. Simply idling with the air conditioning on is indeed more harmful to the car than driving. When the engine runs at a low speed of 800 RPM, the oil pump doesn't rotate fast enough, allowing oil and gasoline vapors from the crankcase to enter the cylinders, gradually leading to carbon buildup. This is especially true for older vehicles, which are also prone to higher coolant temperatures. Once, I saw a car owner nap in the car for two hours with the air conditioning on, and in the end, the battery was drained, leaving the car unable to start. I recommend maintaining at least 1500 RPM when using the air conditioning or driving around for five minutes every half hour.
Last month, my car got damaged exactly like this! On the weekend, I took my kid to tutoring class and waited in the parking lot with the AC on for three hours. The next day, the car started shaking when I turned it on. The mechanic said all the spark plugs were clogged with carbon deposits. At idle speed, the alternator doesn't provide enough power, and running the AC consumes extra electricity, keeping the battery chronically undercharged. Plus, the exhaust pipe stays too cold, making it prone to water accumulation and corrosion. Now I bring a folding chair and wait under the shade of a tree. If I really need to use the AC, I keep the windows open for ventilation.
