MACS 609 Certification Practice Exam

Using a soapy water solution to check for refrigerant leaks in an A/C system is effective because the solution creates bubbles at the site of any leaks. When refrigerant escapes from a system, it passes through tiny openings, and when it comes into contact with the soapy water, the gas causes the formation of bubbles. This visually indicates the presence of a leak, making it a straightforward and practical method for technicians to determine whether there's a need for repair or further inspection.

Other substances, like water or alcohol, do not provide the same level of visibility for detecting leaks because they don't produce bubbles in response to escaping gas. Mineral oil may not interact with refrigerants in a way that highlights their presence, making it far less suitable for this purpose. The effectiveness of the soapy water solution makes it a preferred choice for identifying leaks in HVAC systems.