Q: AC not working.

An A/C system can be divided into 3 different sub systems. These sub systems work for the most part independent from each other. The heater part of it works off of water from your engine. The refrigerant part is what makes the air cold, it is a sealed system that works similar to you home refrigerator. The last sub system is the duct and fan. This is what directs the air to the vent/floor/defroster, and actually blows the air. If the refrigerant system is low, a pressure sensor will detect this and not allow the system to come on. A technician will have the proper equipment to recharge your system and find the leak. Usually electronic leak detection equipment or ultraviolet dyes are used for this. Another common issue is actuator failure. Actuators are part of the duct system. They direct air from to the proper areas for cooling or heating. If the door that directs the hot/cold air is stuck half way or on the hot side because of actuator failure, it will blow warm/hot even if the refrigerant side is doing its job. Actuators can be difficult to get to as they are behind the dashboard usually. There are also several of them so seeking help from a technician is advised.