Typically, air conditioning units are designed to cool the air rather than heat it. They work by removing heat from the indoor environment and releasing it outside. Therefore, a standard air conditioning unit set to 30 degrees Celsius would not be able to heat a room in the winter.
However, it's worth noting that some modern air conditioning systems are equipped with a heat pump feature, commonly referred to as a "reversible" or "heating mode" function. These units can provide both cooling and heating capabilities. In the heating mode, the air conditioner absorbs heat from the outside air (even in cold temperatures) and releases it into the room, effectively warming the space.
So, if you have an air conditioning unit with a heating mode, it may be possible to use it to heat a room in the winter. However, it's important to check the specifications and capabilities of your specific air conditioner to determine if it has this feature. Additionally, the heating efficiency of such units may vary, and they may not be as efficient as dedicated heating systems, such as furnaces or heaters.