No, an air conditioner does not warm the air. Its primary function is to cool the air inside a room or a building. If the outside temperature is lower than the set temperature on the air conditioner, the air conditioner will not turn on because there is no need to cool the already cooler air further.
When you set a temperature on the air conditioner, it operates by extracting heat from the indoor air and releasing it outside, making the indoor environment cooler. If the outside temperature is already lower than the set temperature, the air conditioner will simply remain idle or may operate in a fan-only mode to circulate the cool outdoor air without any cooling action.
If you want to warm the air inside your home when the outside temperature is lower, you would need to use a heating system, such as a furnace, space heater, or heat pump, depending on the type of heating system you have. Heating systems are designed to increase the temperature of the indoor air by generating or transferring heat into the living space.