Indoor unit displays E5; compressor may not start or shuts down quickly; sometimes accompanied by humming from outdoor unit.

Critical safety: This fault involves high voltage and high current. Always shut off power at the breaker and outdoor disconnect. Do not touch compressor terminals with power applied.

• Step 1 – Power reset: Turn off power for 10 minutes to allow the inverter module to discharge. Restore power and test. If E5 returns immediately, proceed.
• Step 2 – Check supply voltage: Have a qualified person verify correct line voltage at the outdoor unit (per Senville nameplate). Low or unstable voltage can trigger E5.
• Step 3 – Inspect wiring: With power OFF, inspect compressor wires and terminal cover. Look for burnt connectors, loose spade terminals, or melted insulation. Repair or replace damaged wiring.
• Step 4 – Check outdoor PCB: Inspect the inverter/power section of the outdoor PCB for burn marks, cracked components, or bulging capacitors. A damaged board typically requires replacement.
• Step 5 – Compressor evaluation: If wiring and PCB appear normal but E5 persists, the compressor windings may be shorted or the compressor may be mechanically locked. This requires professional diagnosis with a meter and likely compressor or outdoor unit replacement.

Because of the electrical hazards and cost of parts, E5 faults are best handled by a licensed HVAC technician.