Apr 3
Advanced Multimeter Techniques for HVAC and Appliance Diagnostics
What Your Multimeter Can Do That You're Not Using
Most techs use V, ohms, continuity. Here's what else is in there:
Capacitance (MFD) — Catches partial cap failure. Replace at 10% below rated value. Discharge first.
Amp clamp — Compare to motor FLA nameplate. Above = binding/worn bearing. Below on loaded motor = open winding.
K-type temp probe — Superheat + subcooling without a separate thermometer. Two measurements, one diagnostic quadrant.
Millivolts DC — Standing pilot thermocouple output. Normal: 25-35 mV. Below 17 mV = replace. $8-15 part.
Full guide with 5 field scenarios at ServiceMag
