A vital component of your car’s A/C system is the thermal expansion valve, otherwise known as a TXV, or simply TX, valve. For your A/C to work, the evaporator must receive enough refrigerant to be able to create the cool air that's pumped into your car. The TXV valve works by way of a pin that, depending on the settings you choose on your A/C system, restricts the flow of the liquid. When you turn your A/C on, the valve pin allows the appropriate amount of refrigerant to enter the evaporator, which is where your cool air is formed. If you are not receiving any cool air from your A/C system, it is likely that your TXV or control valve is faulty and needs replacing.