Indoor/outdoor unit communication error (Outdoor unit transmitting)

What does E9 mean?

This indicates a communication error where the outdoor unit transmits but receives a continuous '0' (30 times) or fails to find a transmission path for 10 minutes. Common causes include wiring issues between indoor/outdoor units, noise interference, or a defective communication circuit on the outdoor controller board. This prevents crucial operational data exchange, leading to system shutdown or erratic behavior.

Complete Troubleshooting Guide

1. 1

   Thoroughly check the indoor/outdoor unit connecting wire for disconnections, looseness, or damage.

2. 2

   Cycle the power off and on to reset the communication.

3. 3

   Investigate potential sources of electrical noise entering the power supply or communication wires.

4. 4

   If the abnormality persists after the above steps, replace the outdoor controller circuit board.