why does warning lights say air conditinor off to prevent damage to engine

Hello, Saturn does that when the the engine coolant temperature sensor says the engine is too hot. If there is any overheating, at any point, or if the engine control module thinks the thermostat is stuck closed, the air conditioner will be turned off to prevent overheating. The check engine light should be on, and there should be trouble codes stored on the engine control module for retrieval.