PURPOSE: An air conditioner system for a truck is provided to prevent noise and exhaust gas due to the driving of an engine when an air conditioner is operated. CONSTITUTION: An air conditioner system for a truck comprises an outdoor unit(10) and an indoor unit(20). The outdoor unit liquidizes refrigerant compressed by a compressor. The outdoor unit is installed on a back-panel or the roof of a cabin(C) of a truck(T). The indoor unit cools the inside of the cabin of the truck and is installed inside the cabin. A harmful gas sensor is installed in the indoor unit. The harmful gas sensor senses the concentration of harmful gases, including carbon dioxide, inside the cabin and informs passengers.
