Copyright Goodheart-Willcox Co., Inc. 380 Motors and Electric Control Systems operating diode, the red meter lead is connected to the diode’s anode (positive lead), and the black meter lead is connected to the diode’s cathode (negative lead). If the meter registers a voltage for both meter lead configurations, then the diode conducts in both directions and must be replaced. If the meter does not register a voltage in either direction, then the diode does not conduct and must be replaced. Continuity Check Continuity is the condition that exists when there is a con- tinuous, unbroken path between two points in a circuit. A cir- cuit that has continuity is also referred to as a closed circuit because the circuit is complete. The continuity check function on a multimeter is used for quick checks to see if there is a defi- nite connection between two points in a circuit. Occasionally, meters will display the resistance between the points being checked however, the most common and notable indication of whether continuity exists is an audible beeping. If the mul- timeter does not beep, it means the circuit is open. Continuity check AC microamps AC milliamps AC amps Capacitance Frequency check Resistance Diode check AC volts DC volts DC millivolts Off High-current terminal—above 1 A (red lead) Low-current terminal—below 1 A (red lead) Function indicator Voltage, resistance, capacitance, and frequency terminal (red lead) Common terminal (black lead) Temperature function Milwaukee Electric Tool Corp. Figure 17-8. HVACR technicians commonly use multimeters that have a thermocouple attachment to use with a temperature measurement function. Sealed Unit Parts Co., Inc. Figure 17-7. An HVACR technician must be familiar with the numerous functions and settings on a digital multimeter.