Will Not Turning Off the AC Before Shutting Down the Car Cause Starting Issues?
2 Answers
If the AC is left on when the car is turned off, some car owners may find the AC still running the next time they start the car, raising concerns about potential harm. Today, we’ll discuss this issue. As usual, we’ll first explain the principle, so everyone can understand how to proceed. Here’s additional information: Operational Note: This applies to automatic AC systems as well. Although automatic AC doesn’t have a mechanical switch, it has a memory function. If the OFF button isn’t pressed when parking, the AC will continue running upon the next vehicle start. Additionally, the blower will operate when the key is turned to the ON position.
I've driven several cars and found that turning off the engine without turning off the air conditioning usually doesn't directly prevent the car from starting. However, if the air conditioning is still on during the startup moment, it will consume more battery power. Starting the engine requires a large current, and running the air conditioning compressor simultaneously adds to the load. If the battery is low on charge or aging, such as after three or four years of use, it may cause difficulty starting or even failure. This is similar to how using too many appliances at home can trip the circuit breaker. I recommend developing the habit of turning off the air conditioning before shutting down the engine, especially when the battery condition is poor or the weather is cold, to reduce this risk. Regular battery maintenance is also important—check the voltage and terminal connections periodically, clean any corroded parts, and ensure reliable starting. These small habits can extend battery life, prevent unexpected breakdowns, and make driving more worry-free.
