COMPONENT FAULT ISOLATION CHECKS AND RESISTIVE/ INDUCTIVE LOAD AND SWITCHING DEVICE MEASUREMENTS

Purpose – This procedure describes checks and measurements used when troubleshooting an electrical problem located in the load or control circuits o f HVAC equipment. It also describes the measurements needed to confirm whether a component is open, shorted, or good. Confirmation that a component is defective is necessary because faulty wiring connected to the component can also be the cause of a problem.

The procedures in this section assume that the source of an electrical problem has already been isolated to the malfunctioning circuit either by performing Service Procedure SP-7, or through analysis o f the system operating conditions. The troubleshooting in this procedure covers the types of components listed below.
• Resistive loads, such as crankcase heaters and heater elements.
• Inductive loads, such as relay/solenoid coils, transformer windings, etc.
• Switches and contactor/relay-actuated switched contacts.


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