There can be several reasons why a car may shut off when the air conditioning (AC) is turned on and the vehicle is at a complete stop. Here are a few possible explanations:
Idle Speed Control: When the AC is engaged, it puts an additional load on the engine. If the idle speed control system is not functioning properly or if the idle speed is set too low, the engine may struggle to maintain a stable idle speed and eventually stall.
Electrical Issues: The AC system relies on various electrical components to function, including sensors, relays, and the compressor clutch. If there is an electrical problem or a faulty component within the AC system, it could lead to an interruption in the electrical supply to the engine, causing it to shut off.
Overheating: The AC system generates heat, and if the engine cooling system is not operating efficiently or if there is a coolant leak, the engine may overheat when the AC is on. Modern cars are equipped with sensors that can detect overheating and automatically shut off the engine to prevent damage.
Low Engine Performance: If the engine is not running optimally, such as due to a clogged fuel filter, a malfunctioning fuel pump, or a faulty ignition system, the additional load imposed by the AC system can exacerbate the problem and cause the engine to shut off.
It's important to have a qualified mechanic inspect your vehicle to diagnose and address the specific cause of the stalling issue. They can perform a comprehensive check of the engine, electrical system, and AC system to determine the underlying problem and provide appropriate repairs.