* Low battery voltage/alternator problems: The AC compressor is a significant power draw. If your battery is weak or your alternator isn't charging properly, the sudden increase in electrical demand when you turn on the AC can cause the engine to stall due to insufficient power. This is a very common cause.
* Failing AC compressor: A seized or severely damaged AC compressor can draw excessive current, leading to the engine stalling. This is less common but more serious than a battery or alternator issue.
* Engine problems unrelated to AC: While less likely to *only* occur when the AC is on, underlying engine issues like low fuel pressure, insufficient air intake, or other mechanical problems can be exacerbated by the additional load of the AC compressor. The engine might be running on the edge already.
* Faulty AC clutch: The AC compressor is engaged by a clutch. If this clutch is malfunctioning, it might draw excessive current, overloading the system.
* Loose or corroded battery terminals/cables: Poor connections can lead to voltage drops under load.
* Wiring problems: Issues in the wiring harness related to the AC system could cause a sudden surge or short circuit.
In short: The engine shouldn't shut off simply because the AC is turned on. This is a sign of a problem that needs to be diagnosed and repaired by a qualified mechanic. Ignoring it could lead to more serious damage.
