How do you test an HVAC transformer with a multimeter?

To test a furnace transformer with a multimeter, ensure the power is turned off for safety. Set your multimeter to the appropriate AC voltage setting. First, measure the primary side by placing the multimeter probes on the input terminals of the transformer; you should see a reading that corresponds to the voltage supply (typically 120V or 240V). Next, test the secondary side by measuring across the output terminals; it should read the transformer’s output voltage (often 24V for HVAC systems). If the readings are significantly lower than expected or zero, the transformer may be faulty and require further inspection or replacement. Always remember to follow safety procedures and manufacturer guidelines during testing.