Air Conditioning Repair Certification (ETI) Practice Exam

The commonly used instrument for measuring refrigerant pressure is a pressure gauge. This tool is specifically designed to provide accurate readings of the pressure within the refrigerant system, which is essential for diagnosing and maintaining air conditioning systems. Understanding the refrigerant pressure is crucial for technicians, as it helps assess the system's performance, detect potential issues such as leaks or blockages, and ensure that the system operates within the manufacturer's specified pressure range.

In contrast, a multimeter is used for measuring electrical properties like voltage, current, and resistance, which does not apply to refrigerant pressure measurement. A thermometer measures temperature, another important aspect of HVAC systems but not directly related to pressure readings. A tachometer, on the other hand, measures rotational speed and is not suitable for assessing pressure within a refrigerant system. Thus, the pressure gauge stands out as the appropriate choice for evaluating refrigerant pressure.