U4 - Outdoor thermistor short/open circuit

What does U4-2 mean?

The outdoor thermistor, which measures the ambient temperature, has a short or open circuit. This prevents the system from accurately sensing external conditions, affecting performance.

• Damaged outdoor thermistor.
• Loose or corroded wiring connections to the thermistor.
• Faulty outdoor unit PCB connection.

Click steps to track your progress.

1. 1

   Turn off the air conditioning unit at its dedicated circuit breaker for 30 seconds.

2. 2

   Restore power and restart the unit.

3. 3

   If the error persists, contact a service technician to inspect and potentially replace the outdoor thermistor.