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Discharge Pipe Resonance Audible Noise (500–1000 Hz Band)

Likely causes

Discharge pipe length/shape matches pulsation frequency — resonance occurs

Check: Grip pipe sections briefly with hand while listening — if metallic noise changes, that section is resonance point; measure with smartphone spectrum app — confirm 500–1000 Hz peak

What to do: Insert rubber pad (3–5 mm) between pipe and frame, or adjust clamp positions; reinstall clamps at 600 mm or less spacing (shorten free span → shift resonance frequency); add flexible joint at compressor-to-pipe connection

Inverter passes through resonant RPM range

Check: Confirm noise spikes at specific RPM when compressor speed varies — typical pattern of passing through resonance point; sustained noise when locked at that RPM

What to do: For inverter units: configure Skip Frequency function to avoid resonant RPM range; without inverter, adding clamps is the fastest field fix

Field tip

Discharge pipe resonance location can be identified without a spectrum analyzer by the change in metallic sound when gripped by hand — adding a clamp is the fastest field fix.

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