Does idling a diesel car with the AC on damage the vehicle?

[AdrianFitz]

Idling a diesel car with the air conditioning on can cause damage to the vehicle. It can lead to excessive pressure in the cooling system, resulting in elevated engine temperature and excessive carbon buildup. Additionally, it can cause poor air circulation inside the car, which over time may lead to carbon monoxide poisoning. When a diesel car idles with the AC on, it first places significant stress on the cooling system. Since the air conditioning compressor has a high power demand, it substantially increases the load on the vehicle. A higher engine load requires a richer air-fuel mixture to generate more power, which in turn produces more heat. Since the car remains stationary, the heat can only be dissipated by the cooling fan blowing air through the radiator, forcing the cooling system to operate continuously under heavy load. If the cooling system has even minor issues, it can lead to higher engine temperatures, adversely affecting the engine. Moreover, a richer air-fuel mixture results in incomplete combustion of fuel, leading to increased carbon deposits over time. Even without the AC on, prolonged idling can cause carbon buildup, and turning on the AC further increases engine load, exacerbating incomplete combustion and accelerating carbon deposit formation and retention. Extended idling with the AC on can also make the air inside the car stale. If the vehicle is parked in a poorly ventilated area, the risk of carbon monoxide poisoning increases. Car exhaust contains carbon monoxide, and if the vehicle remains stationary, the concentration of carbon monoxide in the surrounding air rises. When the AC is turned on, outside air enters the cabin, increasing the carbon monoxide levels inside the car.