Outdoor condensing unit with a large fan on a steel stand
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Reading amp draw on a motor or compressor: nameplate RLA/FLA is a ceiling, not a target

The current on a motor or compressor nameplate (FLA, or RLA on compressors) is a rating used to size wiring and protection; running current should not exceed it, but a healthy unit often runs well below it. Starting current (LRA, locked-rotor amps) is a brief surge many times higher. Compare what you measure with the nameplate as an upper limit, with the maker's expected current for the actual conditions where it exists, and with a known-good identical unit. This guide is electrical measurement only; anything inside the sealed system is EPA 608 work.

Cross-checked ~20 min moderateBrands: All

Before you start

  • Clamp one conductor only; clamping a cord with both conductors reads near zero
  • Line-voltage compartments are live during the test; keep hands clear of fan blades and terminals
  • Refrigerant pressures, charge and sealed-system repair are blocked: refer to an EPA 608 certified technician

Diagnostic steps

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OnCall Tech is a reference tool for trained technicians and can make mistakes. Always disconnect power and confirm with the manufacturer's documentation before you work.

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Reading amp draw on a motor or compressor: nameplate RLA/FLA is a ceiling, not a target · OnCall Tech