Warm air could be caused by a refrigerant leak, system blockage, or a faulty component such as a compressor. (The compressor is a pump that pumps the refrigerant chemical through the system.) Low air volume means that the air stream being fed into the vehicle cabin is impeded by something, such as a faulty air duct door or clogged air vent.
Do you need to recharge the A/C? If your air conditioner needs recharging, it is because the refrigerant chemical is leaking out of the system. Many people think that air conditioners naturally leak refrigerant, so they assume they have to take the car in every year for recharging. This is not true. The refrigerant is not supposed to leak. If the refrigerant is low, we find the leak by recharging your system and adding dye. The dye allows us to see where the refrigerant is leaking, then we repair the leak. There should be no reason for a recharge.