How to Test Condenser Motor Windings with a MultimeterWhen a capacitor replacement doesn’t fix the problem, the next step is testing the motor’s windings. A winding test tells you whether the motor has an open circuit, a short circuit to ground, or a phase-to-phase short.Understanding the TerminalsMost condenser fan motors have three terminals:Common (C) — Shared return for both windingsRun (R) — Connected to the run windingStart (S) — Connected to the start windingThe relationship between resistances should be:R(C–S) + R(C–R) = R(S–R) (approximately)This is because the start and run windings are wired in series between S and R.Test 1 — Resistance Check (DMM on Ohms)With the motor disconnected from all wiring:Measure resistance between C and R (run winding).Measure resistance between C and S (start winding).Measure resistance between S and R.Acceptable results:All three readings show finite resistance (typically 1–30 ohms depending on motor size).R(S–R) ≈ R(C–S) + R(C–R).Fault indicators:OL (overload/infinity) on any reading → open winding; motor must be replaced.Zero or near-zero ohms between any two terminals (other than expected values) → winding short.Test 2 — Ground Insulation Check (DMM on Ohms)Set your DMM to the highest resistance range (or use a Megger):Connect one probe to any motor terminal.Touch the other probe to the motor frame/housing (bare metal).Repeat for all terminals.Acceptable result: Infinite resistance (OL). Any measurable resistance — especially below 1 MΩ — indicates compromised insulation, likely due to moisture ingress or overheating. The motor should be replaced.Test 3 — Amperage Under LoadRestore power temporarily and, using a clamp meter around one motor lead:Compare measured amperage to the FLA (Full Load Amps) on the nameplate.Amperage significantly above FLA indicates the motor is working harder than it should — possible causes include a failing bearing, incorrect voltage, or a locked rotor condition.