Error Code: EL 01 – Indoor & Outdoor Unit Communication Error

Error Code: EL 01 – Indoor & Outdoor Unit Communication Error

What this means:
The indoor unit is not receiving any feedback from the outdoor unit for 110 seconds — and this occurs four times in a row. This communication failure is typically caused by incorrect wiring, a faulty PCB, or power supply issues between units.

Try this first (quick reset):

1. Turn off power to the unit using the circuit breaker.

2. Wait 2 full minutes.

3. Turn the unit back on and check if the error clears.

• If the error clears — it may have been a temporary power or signal fault.

• If the error remains — follow the steps below.

Next steps (for technicians):

1. Check all terminal wiring:

   • Verify wiring between indoor and outdoor terminals matches the wiring diagram.

   • Reconnect any loose or incorrect wires.

2. Measure signal voltage (Vs):

   • Measure voltage between S and N terminals.

   • If Vs alternates between positive and negative → signal is normal.

   • If fixed or missing → continue troubleshooting.

3. Check the IPM board LED:

   • If LED is off → replace the IPM board or outdoor main PCB.

   • If LED is on → continue to next step.

4. Verify number of indoor units:

   • Check outdoor board to confirm all expected indoor units are detected.

   • Example: 2 for dual zone, 3 for tri-zone, etc.

5. Check the reactor connection:

   • If disconnected → reconnect.

   • Measure resistance (should be close to 0 ohm).

   • If not → replace the reactor.

6. If all steps pass but error remains:

   • Replace the indoor PCB or outdoor PCB.

What you might need:

• Indoor PCB

• Outdoor PCB

• IPM module board

• Reactor

• Connection wires

Helpful tip:
Use a multimeter to test the reactor’s resistance (disconnected from capacitor). If it’s not near zero ohms, the reactor is likely faulty.

Click here to view the detailed guide.TS13