Outdoor Board LED1 (green) blinks four times and LED2 (red) blinks four times alternately - Open/short of discharge thermistor (TH4)

What does U5 mean?

During startup or operation, the outdoor unit's LED1 (green) blinks four times and LED2 (red) blinks four times alternately, indicating an open circuit or short circuit in the discharge thermistor (TH4).

• Open circuit in discharge thermistor (TH4).
• Short circuit in discharge thermistor (TH4).
• Disconnected connector for TH4.

Click steps to track your progress.

1. 1

   Check if connectors (TH3, TH32, TH33, TH4, and TH7/6) on the outdoor controller board and connector (CN3) on the outdoor power board are not disconnected.

2. 2

   Measure the resistance value of the outdoor thermistor (TH4) using a tester.

3. 3

   Ensure the discharge thermistor is securely placed and its wiring is intact.