Scroll Compressor Reverse Rotation — 3-Phase Miswiring

Question

Accepted Answer

3-phase R·S·T wiring sequence reversed → motor runs backward, no refrigerant compression. Check: Within 30 sec of start: no discharge pressure rise (below 10% of normal), no suction pressure drop, metallic scraping noise. Current stays normal (±5%) — easy to misdiagnose What to do: Cut 3-phase power → swap two phases (R·S or S·T) and reconnect → after restart, confirm suction drops and discharge rises within 30 sec (R-22: discharge 14~18 kgf/cm²) Prolonged reverse rotation wears tip seals — capacity loss. Check: If reverse rotation history, check compression ratio — capacity loss 15~30% vs normal. If discharge temp below 70°C (normal 90~110°C), suspect tip seal damage What to do: Replace compressor or overhaul with new tip seals. Prevention: install phase sequence relay

Scroll Compressor Reverse Rotation — 3-Phase Miswiring

Likely causes

3-phase R·S·T wiring sequence reversed → motor runs backward, no refrigerant compression

Prolonged reverse rotation wears tip seals — capacity loss

Related cases