Does running the air conditioning at idle speed affect the engine?
3 Answers
Running the air conditioning at idle speed does affect the engine. Here is a partial introduction about the car air conditioning: Lack of refrigerant or leaks: Most cases of insufficient cooling are due to a lack of refrigerant. You can first test the air conditioning pressure. If both high and low pressures are low, it is basically due to insufficient refrigerant, and you just need to add refrigerant until the pressure is appropriate. Excessive pressure in the air conditioning system: The car air conditioning system has its own pressure due to the compressor's operation. When too much refrigerant is added or there is a blockage in the pipeline, the system pressure can become too high. In this case, the control system will disconnect the compressor's electromagnetic clutch to stop the compressor. The solution is simple: after confirming that the pressure exceeds the standard, release some refrigerant to restore normal pressure. Damaged evaporator temperature sensor or pressure switch: The evaporator, also known as the evaporator box, is located in the air duct under the dashboard. The refrigerant vaporizes here, absorbing heat and producing low temperatures. When airflow passes through the small channels on the evaporator, it is cooled. The compressor stops when the temperature approaches the frost point. If this sensor is damaged and frequently gives false alarms about approaching the frost point, the compressor will frequently stop.
As someone who has been working in car factories for years, I believe idling with the AC on can have a significant impact on the engine. At idle, the engine runs at low RPM with weak power output. When the AC compressor kicks in, it adds extra load, making the engine work harder, which may increase fuel consumption and carbon buildup issues. Occasional short-term use is fine, but prolonged idling with the AC puts heavy strain on the engine, reducing lubrication and cooling efficiency, which can lead to premature wear of components like piston ring oil coking or spark plug carbon deposits. Additionally, it drains the battery faster, and a dead battery could cause trouble. For the sake of engine health, I recommend avoiding long periods of idling with the AC on. If you must use it, turn off the AC to let the car cool down before restarting—this saves fuel and protects the engine. Regular maintenance can also prevent potential issues.
As a veteran driver with over 20 years of experience, I can confirm that idling with the AC on does have consequences. One summer day stuck in traffic, I idled with the AC running for half an hour – afterwards, the engine sounded rougher and fuel consumption skyrocketed. At low RPMs, the engine has to work extra hard to power the AC compressor, increasing load and burning more fuel while also producing more exhaust pollutants. Long-term, this accelerated wear could shorten engine lifespan, like forcing a machine to operate beyond capacity. However, brief periods like waiting at red lights for a few minutes are negligible. The key is timely AC shutdown or engine turn-off to prevent overheating, saving fuel and protecting your vehicle. While newer car designs handle this better, older models are more sensitive.
