Refrigerant blends need to be charged as a liquid.

• A. False
• B. True
• C. Only during startup
• D. Never

Answer: (B)

Charging refrigerant blends as a liquid keeps the mixture’s composition uniform as it enters and circulates through the system. These blends are made of components that boil at different temperatures, so if you introduce the charge as a gas, the components tend to vaporize at different rates and separate (fractionate). That separation changes the actual ratio of the refrigerants in the system, which can lead to incorrect pressures, reduced cooling performance, and potential compressor or lubrication issues. By charging as a liquid, you preserve the intended mix, and the system can vaporize the liquid in a more controlled way, maintaining the designed operating characteristics. In practice, most service procedures call for liquid charging (often through the liquid line or by weighing the charge) to minimize fractionation and ensure correct performance.