Error Code: EC 53 – Outdoor Ambient Temperature Sensor (T4) Error

Error Code: EC 53 – Outdoor Ambient Temperature Sensor (T4) Error

What this means:
The outdoor ambient temperature sensor (T4) is not functioning correctly. This error occurs when the sensor’s voltage reading is below 0.06V or above 4.94V, indicating a possible open circuit, short circuit, or sensor failure.

Try this first (quick reset):

1. Turn off power to the unit completely.

2. Wait 2 full minutes.

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

• If the error clears — the issue may have been temporary.

• If the error returns — follow the steps below.

Next steps (for technicians):

1. Inspect wiring between T4 sensor and PCB:

   • Make sure the sensor is properly connected and not damaged.

   • Repair or replace connection wires if needed.

2. Measure the resistance of the T4 sensor:

   • If resistance is out of acceptable range → replace the T4 sensor.

   • If resistance is normal but error remains → replace the outdoor PCB.

What you might need:

• T4 ambient temperature sensor

• Outdoor PCB

• Connection wires

Helpful tip:
EC 53 is part of a family of sensor-related faults. If your model uses a combination sensor (T3, T4, TP), replacing one may require replacing the entire sensor module.

Click here to view the detailed guide.TS18