Is it okay to idle a car with the air conditioning on for a long time?
2 Answers
It is not advisable to idle a car with the air conditioning on for extended periods. When the engine is idling, the fuel does not burn completely, and the exhaust often contains a large amount of carbon monoxide. The carbon monoxide emitted with the exhaust can accumulate around the vehicle and enter the cabin through the air conditioning system. Additionally, with the windows closed while the air conditioning is on, the air does not circulate, and over time, the concentration of carbon monoxide in the cabin can become increasingly high, posing a risk to human health. Below are some tips for air conditioning maintenance: 1. Comprehensive air conditioning inspection: When using the air conditioning for the first time in summer, check the air conditioning system thoroughly. For example, inspect the refrigerant through the reservoir, check if the air filter is dirty, and see if there are any foreign objects in the radiator. 2. Pay attention to air conditioning cleaning: The air filter should be replaced regularly to prevent moldy odors from developing in the air conditioning system. Additionally, the condenser should be cleaned periodically, and it is best to remove the radiator for a thorough cleaning.
I had an old car that developed issues from idling with the AC on for too long. That time, I took a half-hour nap at a highway rest area with the AC running, only to wake up and find the fuel consumption had spiked significantly. Later, during maintenance, the mechanic pointed out that the engine had more carbon buildup than usual. He explained that at idle, the engine runs at low RPM, leading to incomplete fuel combustion, which particularly promotes the accumulation of gummy deposits on the fuel injectors and throttle body. The continuous operation of the AC compressor also increases the engine load, causing the coolant temperature to rise. Most critically, the concentration of carbon monoxide in the exhaust under such conditions is exceptionally high—dangerously so in an enclosed garage. Now, I limit idling with the AC to no more than 10 minutes and make it a habit to turn off the engine and step out of the car whenever possible.
