Indoor unit displays E1 and stops cooling; fan may still run but compressor does not start.

Safety first: Turn off power to the Senville air conditioner at the breaker and use a non-contact voltage tester to confirm power is off before touching wiring or boards.

• Step 1 – Power reset: Turn off the breaker for 5–10 minutes, then restore power. Sometimes E1 is a transient communication error.
• Step 2 – Inspect communication cable: Remove the indoor unit front cover and access the terminal block. Verify the communication terminals (often labeled 1-2-3 or S1-S2-S3) are tight and wires are not burnt or corroded. Repeat at the outdoor unit terminal block.
• Step 3 – Check polarity and matching: Ensure the same wire color goes to the same terminal number between indoor and outdoor units. Incorrect polarity or mis-matched terminals will cause E1.
• Step 4 – Inspect cable condition: Follow the communication cable along its route. Look for cuts, rodent damage, crushed insulation, or water ingress at junction boxes. Replace the cable if any damage is found.
• Step 5 – Board inspection: With power still OFF, visually inspect the indoor and outdoor PCBs for burn marks, swollen capacitors, or melted connectors. If wiring is correct and cable is good, a faulty PCB is likely and should be replaced by a qualified technician.

Do not work on live circuits. If you are not comfortable with electrical diagnostics, contact a licensed HVAC technician.