Mechanic Javier Sendín says starting a car with AC on is safe

Javier Sendín, named Spain's top auto mechanic in 2023, explains that the belief that turning on heating or air‑conditioning while starting a modern vehicle harms the engine is outdated. Modern climate‑control systems are electronically managed; compressors adjust their output to the vehicle’s needs, so starting the engine with the system on does not place extra load.

He adds that occasional use of the climate system can actually help by circulating oil and refrigerant, keeping seals lubricated and preventing leaks. However, he warns that repeatedly driving with a nearly empty fuel tank is far more problematic, as sediment can clog fuel filters and damage common‑rail injection components. Drivers should refuel before the gauge reaches the reserve warning.

The advice applies to contemporary cars equipped with electronic climate control and common‑rail fuel systems.