Ruud air conditioner shows E7; system may not start or may run erratically with fan and compressor cycling unexpectedly.

Safety first: This fault involves high-voltage three-phase power. Only qualified personnel with proper PPE and tools should work on these circuits. Turn off the main disconnect and lock it out before inspection.

• Step 1 – Visual inspection: With power off, inspect the Ruud condenser’s line voltage terminals and contactor lugs for loose screws, discoloration, or melted insulation. Tighten loose connections to manufacturer torque specs.
• Step 2 – Check fuses and breakers: Verify all three fuses in the disconnect are intact and that the upstream breaker is not tripped on any phase.
• Step 3 – Phase monitor module: Many Ruud three-phase units include a phase monitor. Inspect its wiring and LED indicators. If it indicates phase loss or reversal, have an electrician verify incoming power.
• Step 4 – Electrician involvement: An electrician should measure line-to-line voltages and confirm correct phase rotation. If phase reversal is present, they can swap two incoming legs at the disconnect to correct rotation.
• Step 5 – Replace faulty phase monitor: If incoming power is correct but E7 persists and the phase monitor indicates a fault, replace the phase monitor module.