ESCO Air Conditioning Practice Exam

When topping off an operating system containing a blended refrigerant, you should:

1. Introduce the refrigerant as a gas into the high side using the throttling valve

2. Introduce the refrigerant as a liquid into the high side using the throttling valve

3. Introduce the refrigerant as a liquid into the low side using the throttling valve

4. Introduce the refrigerant as a vapor into the low side using the throttling valve

The correct answer is: Introduce the refrigerant as a gas into the high side using the throttling valve

Topping off an operating system with a blended refrigerant means adding small amounts of the refrigerant to maintain the optimal balance. In this case, it is important to introduce the refrigerant as a gas into the high side using the throttling valve. This is because when adding gas, the heat can be drawn out more efficiently and evenly into the system. Introducing it as a liquid into the high side or a vapor into the low side using the throttling valve can lead to uneven distribution and possible damage to the system. Additionally, introducing the refrigerant as a liquid into the low side can cause the refrigerant to flash into a gas too quickly, leading to potential system malfunctions. Therefore, option A is the best and safest method for topping off an operating system with a blended refrigerant.