When your car sputters when the AC is on, it is usually an indication that something is wrong with either the engine, electrical system, or the air conditioning system itself. It is crucial to have the problem diagnosed and fixed by a qualified mechanic to prevent long-term damage and ensure that the AC operates smoothly.

A dirty air filter or spark plug can lead to sputtering when the AC is in use. The air filter helps to keep out dirt and debris from entering the engine and can become clogged over time. The spark plugs are responsible for delivering an electric spark to the engine cylinders to ignite the fuel/air mixture and power the vehicle. Over time, the spark plugs can wear out and require replacement. A poor quality fuel pump or a faulty oxygen sensor can also cause your engine to sputter when the AC is on.

An ac compressor that is not working properly or has low refrigerant levels can put a heavy load on the engine and cause it to sputter. A mechanic can properly diagnose the problem and replace or repair the compressor or refill the refrigerant.

Rough idling can also be caused by a faulty idle air control valve (IAC). The IAC valve is a mechanical component that is responsible for opening and closing the throttle to raise or lower the engine RPM at startup. The IAC valve can become clogged with carbon deposits and cannot open when the AC compressor is running, leading to rough idling. A mechanic can vacuum the IAC valve and remove carbon deposits to restore proper operation.