U4 — Communication error between units

What does U4 mean?

This code means there is a problem with the communication signal between the indoor and outdoor units. This prevents them from working together correctly.

• Loose wiring between indoor and outdoor units
• Damaged communication cable
• Interference with the communication signal

Click steps to track your progress.

1. 1

   Verify that all wiring connections between the indoor and outdoor units are secure.

2. 2

   Inspect the communication cable for any signs of damage or corrosion.

3. 3

   Ensure no strong electromagnetic interference is affecting the communication signal.